Preheat your oven to 350° F (176° C) (if baking immediately).
Saute the sausage and veggies
Dice 1 medium onion and saute it in 1 tbsp of oil over low heat until translucent.
Add 2 cups diced mushrooms and 1 diced green pepper, sprinkle with 1/2 tsp salt, and continue to saute until they begin to release their juices.
Make the tofu mixture
Break up 3 packages of tofu into smaller pieces so it fits in your food processor. (You may have to do this in 2 batches if you don't have a large food processor).
Add 1/2 cup nutritional yeast, 1/4 cup melted margarine, and 2 tsp. salt, and 1/2 tsp pepper, to your food processor and blend. (It will turn into a crumbly grainy mixture).
Slowly add 1/3 cup soy milk, 1 tbsp at a time, blending between each tbsp until the tofu mixture turns from crumbly to a very thick paste.
Add the tofu mixture to the sauteed veggies and sausage along with 1 cup vegan cheese, and 1/2 cup vegan bacon bits. then mix well.
Pour the combined tofu-veggie mixture into a greased casserole dish. (At this point you can store covered in the fridge until ready to bake,)
When ready to bake
Top with a layer of frozen tater tots or hash browns.
Bake at 350° F (176° C) for 1 hour uncovered.
Top with 1 additional cup of vegan cheese and bake covered with foil for another 15 minutes to allow the cheese to melt.
Let it cool for about 10 minutes before cutting to allow it to set a little and firm up.
Notes
This makes a very large casserole meant to serve a large crowd. Feel free to cut the recipe in half and bake it in an 8 x 8-inch baking dish.