Low Carb Gluten Free Squash Casserole with Cheese

INGREDIENTS

medium summer squash (sliced and cooked)

medium zucchini (sliced and cooked)

1 lb

sausage (browned)

1 cup

mayonnaise

1/4 cup

dry minced onion (or 1/2 tsp onion powder)

large egg (beaten)

packet stevia or other sugar substitute

1 tsp

salt

1/4 tsp

pepper

1/4 cup

melted butter

1 1/2 cups

shredded Cheddar cheese (divided)