Double this easily to serve a larger crowd.
Source: Ohio P.E.O. Cooks II cookbook
8 slices firm (or wheat) bread
1-1/4 c. cooked and crumbled bacon (about 1/2 lb.)
8 oz. mozzarella cheese, shredded
8 oz. cheddar cheese, shredded
1-1/2 c. whole milk
1/4 t. dry mustard
1/8 t. onion powder
Trim crusts from bread; cut slices in halves. Grease a 8x8" baking pan and layer as follows: Cover bottom of pan with one-half of bread, one-half of bacon, and one-half of each of the cheeses. Repeat a second layer. Combine eggs, milk, and seasonings. Pour over layers; refrigerate overnight. Remove from refrigerator 30 minutes before baking.
Preheat oven to 375 degrees. Bake for 45-50 minutes. Let stand 10 minutes before cutting into squares.