It is from a medieval cookbook I got from the library, but Mom and I added onions. Slice onions and mushrooms, saute, then mix them up with a few tablespoons of olive oil, half a teaspoon of mustard powder, salt, pepper, and a WHOLE LOT of cheddar cheese. We just used a storebought double crust smeared with beaten egg. Then bake for about 25 minutes at 400 degrees.

Stupid germs. They do get around.