Preheat oven to 350 degrees. Cook the bacon, drain, reserving 3 tablespoons of drippings for the sauce. Grate the cheese, melt the butter, and saute the mushrooms in a little oil for 10 minutes on medium heat.
Mix milk into Bisquik, add beaten eggs, melted butter, grated cheese, sauteed mushrooms, bacon, pepper and salt, and top with cheese.
Use a 12X10X4-inch baking pan. Bake for one hour, cheese should brown. Cut into 3-4 inch square pieces.
Whisk bacon drippings with flour, salt and pepper, cayenne pepper, and nutmeg in a saute pan and simmer until hot.
Put a generous spoonful of the sauce onto a plate and set a square of quiche onto it. Garnish with thinly sliced tomato and serve. Serves 12 people. Just double the pan size and ingredients and serve 24 people.