Vegan Squash Casserole

This healthy vegan squash and zucchini casserole is an easy to make, dump-and-bake, plant-based dinner or side dish the whole family will love. It’s loaded with fresh zucchini, squash, carrots, potatoes, and soy curls in a creamy, dairy-free dijon sauce baked to beautiful bubbling perfection. This zucchini bake is the perfect side dish or ideal meatless dinner for meal prep for the week or to freeze for easy future meals!

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Here I am with another great recipe in our vegan casserole series that uses our vegan condensed soup recipes! This is our vegan version of the southern squash casserole popular at potlucks and church picnics.

In fact, the first time I tried it, I knew I had to share the recipe with all of you! If you like dijon mustard, you’re gonna really love this one!

This casserole recipe is like a traditional squash casserole with a tangy twist. The twist is the dijon-based creamy sauce we use to replace the commonly used sauce usually made from eggs, mayonnaise, heavy cream or whole milk, and sour cream. We also took what is traditionally a side dish and made it a main dish perfect for a complete meal with our addition of vegan chicken and potatoes. 

This is such an easy recipe and one of my favorite ways to use green and yellow summer squash from T’s summer garden! And it’s a great way to use up the last of the tender squash still available as zucchini season ends.

Pin this recipe for later.

Why We Love This Dairy Free Squash Casserole

• It’s an easy casserole to make – Just add everything to a baking dish and bake! This dump and bake casserole is SUCH a simple recipe!
• Healthy – This recipe is loaded with fresh veggies and healthy plant-based protein, although you’d never know it by the taste!
• Loaded with flavor and cozy fall vibes – We love this dish for fall so much! It’s the perfect dinner to snuggle up with on the couch in your sweatpants. But it also feels at home as a side in a fall dinner party!

Ingredients in Zucchini Potato Casserole (Vegan)

You’ll need 11 plant-based ingredients to make this zucchini potato casserole!

• Russet potatoes – Peeled and diced
• Vegan Condensed Cream of Potato Soup – We used our homemade vegan condensed cream of potato! For best results, make this at least a few hours before you make the casserole (ideally, 1 day before), so it has time to thicken properly. If you can’t wait for the vegan condensed potato soup to thicken, you can use the soup out of the blender (just 2 cups, not the whole thing) and reduce the water in this recipe by about 3/4 cup.
• Zucchini, yellow squash, carrot – Shredded with a mandoline on the thin shred or julienne setting.
• Soy curls – Broken into 1/2-inch pieces. Soy curls are our favorite vegan chicken replacement for casserole recipes like this!
• Plain unsweetened non-dairy milk – Make sure you’re using a non-dairy milk that is both unsweetened and plain. A neutral-flavored milk is crucial for this recipe! We like the No Sugar Oat Milk from Chobani, Califia’s unsweetened almond milk, or the unsweetened oat milk from Elmhurst.
• Dijon mustard – Use something with a good quality and flavor, since it’s going to play a starring role in the overall flavor. We are obsessed with Organicville’s dijon mustard.
• Shredded vegan cheese – This is optional but highly encouraged. We used the vegan cheddar shreds from ShopRite’s store brand, but feel free to use your favorite cheese like Violife or Daiya.
• Vegan chicken bouillon powder – We use our homemade vegan bouillon powder!
• Maple syrup – This is optional. We use just a little bit to offset the tangy acidity of the mustard sauce. It’s so good! If you’re adding it, use pure maple syrup and not pancake syrup. Get the good stuff!

Vegan Dijon Mustard Options

Is dijon mustard vegan? Usually, but not always. The base recipe for dijon mustard is vegan, but sometimes companies use a white wine that may not be vegan-friendly. The best bet is to find dijon that uses vinegar in their recipe, the way Organicville does, or has certified the wine used in their product is vegan.

Substitution Options

If you don’t have or can’t tolerate one of the above ingredients, here are our best substitution tips. Remember though, substituting any of the ingredients may lead to a varied degree of difference in the final product. Let us know in the comments if you try any subs and how they work out for you! 

For the potatoes: Sweet potatoes or cauliflower may be a good substitute for the russet potatoes in this recipe. They both cook at different rates though, so be aware of that and adjust the cooking time as you see fit.

For the squash / zucchini: Feel free to use all of one or the other in this recipe.

For the carrots: You can skip this and just add more zucchini/squash. Or if you want something really colorful, try some shredded purple or yellow heirloom carrot mixed with the orange.

For the soy curls: You can sub your favorite vegan chicken but may need to reduce the water a bit, since soy curls come dehydrated and many store-bought vegan chicken pieces don’t. You can usually find soy curls at your local health food store, but we usually just buy them in bulk online. 

For the non-dairy milk: You can sub more water for the non-dairy milk if needed.

For the dijon mustard: Stone ground mustard or whole grain mustard could be good secondary options. A vegan honey mustard would also be nice, but I would remove the maple syrup if you use that! I would stay away from yellow mustard, as that could be a bit overwhelming.

For the vegan cheese: Feel free to skip this!

For the bouillon powder: Skip this or use half as much bouillon paste or 1 bouillon cube.

Condensed Cream of Potato – Options:

You can use any of our condensed soup substitutes for this recipe – especially our vegan cream of chicken! If you’re using a vegan “cream of” soup from the grocery store that’s not condensed, make sure you reduce the water you use. And honestly, I think you could also get away with using leftover mashed potatoes to replace the soup, but you may need to add more liquid to account for texture differences.

How to Make Vegan Squash and Zucchini Casserole

This dump-and-bake vegan casserole is so easy to make – perfect for busy work nights or meal prep!

Step 1: Prepare the ingredients.

If you haven’t already, start by making the vegan condensed cream of potato soup. You can find the full instructions on that here, but to summarize:

Just simmer and blend the ingredients. Then, pour them into 4 (8-oz) mason jars and let them cool. 

Ideally, this should be done at least a few hours before you start the casserole, but you can speed things up by using 2 cups of the potato soup from the blender and reducing the amount of liquid you use in this recipe by 3/4 cup.

When ready to start the casserole, heat the oven to 400°F, and use a mandoline slicer set to the thinner julienne setting to shred the zucchini, squash, carrots.

Step 2: Assemble the casserole.

Stir all the ingredients in a 3-quart casserole dish. Most commonly, a 3-quart casserole dish is a 9×13 inch dish. (That’s the rectangular baking dish common in most kitchens!)

Don’t worry if you can’t break up all the potato soup pieces. Just do the best you can and the oven will do the rest!

Step 3: Bake the casserole.

Cover the baking dish tightly with foil or an oven-safe lid if you have one. 

We’ll bake this zucchini casserole for 40 minutes, covered. After 40 minutes, remove the cover and bake for another 20 minutes until the top is lightly browned.

Step 4: Let it set.

Remove from the oven and put the lid back on top. Let it sit, covered, for 10 minutes. Then, let cool for at least 5 minutes with the cover removed before serving!

How do you keep squash casserole from getting watery?

If your casserole comes out too watery, even after letting it sit the recommended time, there could also be a reason or two:

1. The zucchini or squash you’re using are too big. Try using smaller green and yellow squash. The small yellow squash and like vegetables have less water content and fewer seeds than their larger counterparts. Excess moisture can be removed by lining a small bowl with a paper towel or two and letting the zucchini / squash mixture rest in there while you finish the rest of the ingredients. This simple step can save you a lot of aggravation.
2. Did you omit or substitute the soy curls or other ingredients and remember to adjust the liquid content to reflect that?
3. Another, often overlooked, reason could be temperature calibration in the oven. If you find your recipes often require longer cooking times than suggested, or burn easily, look into this as a potential problem.

The Solution: In any of these cases, put the casserole back in the oven uncovered for a second time and bake for another 5-7 minutes before checking again. Also, sometimes casseroles just need a little time to set after coming out of the oven.

Can squash casserole be frozen before cooking?

I don’t see why not! Assemble everything, mix it together, freeze it in Souper Cubes or foil-lined baking dish. Pop out when frozen. To cook: Let thaw in the fridge overnight and cook as directed.

How to Serve Shredded Zucchini Casserole (Vegan)

Serve this vegan squash casserole hot (after the initial 15 minute cooling time!) sprinkled with some vegan parmesan cheese or fresh herbs like thyme or parsley for a little extra color! You can also top with some crumbled ritz crackers or panko bread crumbs with Italian seasoning and garlic salt.

What to Serve with Squash Casserole

• A hearty bowl of vegetable soup
• A big salad with vegan caesar, dairy-free ranch, or homemade Italian dressing
• Cheesy Vegan Breadsticks

How to Store Leftover Zucchini Squash Casserole

This makes 6 large servings for very hungry people or 8 modest servings. And just like any good casserole, leftovers store great! 

In the Fridge: Store leftover squash casserole in an air-tight container in the fridge for up to 3-4 days. 

To Reheat: Reheat in the oven or microwave. If you are using the oven, preheat it to 400 F and reheat, covered, in an oven-safe dish for about 10-15 minutes until warmed through. If microwaving, reheat at about 70-80% power (med high) for 2-3 minutes until warmed through.

Can you freeze zucchini casserole?

Yes! Make a double batch and freeze one for a future dinner, or freeze it in single servings for a great make-ahead lunch. It should stay fresh for at least 6 weeks! 

You can also bake this casserole right in your 1-cup or 2-cup Souper Cubes! Just mix everything in a bowl, and transfer to the cubes to bake. You may need to adjust the time. But once done, just let the casserole servings cool completely and then freeze completely. You can then pop them out and have the perfect casserole serving any time!

To reheat from the freezer: Defrost in the microwave on a medium to medium low power setting. About 40-50% power for 2-3 minutes until mostly thawed through. Then you can reheat at 70-80% power for 2-3 minutes until warm. If using the oven, preheat to 400F and reheat the casserole covered in an oven-safe dish for about 30-40 minutes until warmed through.

More Savory Zucchini Recipes

• Vegan Zucchini Lasagna

We hope you and your family love this squash and zucchini casserole and find it as deliciously comforting as we have!

When you make it, we would love to hear what you think! Don’t forget to leave a star rating and review on the recipe below. It helps more people to find our recipes, and we just love cheering you on in your vegan kitchen wins!

Watch our Creamy Dijon Veggie Casserole web story here.