Step 1: Add all ingredients, except the cheese and mustard, to a saucepan. Bring to a full rolling boil, then turn heat to low and simmer (covered) for 10 minutes
Step 2: Once cooked, carefully transfer the contents of the pot to a heat-safe blender and add the vegan cheddar and mustard.
Blend, starting on a low speed and slowly increasing to high, for about 1 minute. The soup mixture will be fully smooth and creamy like this!
Step 3: Pour this vegan cream of cheddar into 4 (8-oz.) mason jars, leaving 1/2 inch of space at the top of the jars. Cover with lids and let them cool completely on the counter.
Once cooled, refrigerate for at least 1-2 hours to fully thicken. Then, use this vegan cream of cheddar as a 1:1 sub for the Campbell's version in all the casseroles!