Prepare day ahead and pop in the oven on a holiday morning! You may substitute ham or sausage for the bacon or the broccoli if you wish.
Place bacon in a large, deep skillet. Cook over medium high heat until evenly brown. Drain, crumble and set aside.
Place a colander and two cups of water in a small stock pot. Add the broccoli and bring water to a boil. Cook until tender but still firm, about 10 minutes. Drain, cool and chop.
Lightly butter a 9x13 inch baking pan. Lightly butter bread slices. Line bottom of baking pan with bread slices. Cover bread with cheese, bacon and broccoli.
In a large bowl, beat together eggs, milk, mustard, salt and pepper. Pour egg mixture into pan. Refrigerate overnight or bake immediately.
Twenty minutes before baking, preheat oven to 325 degrees F (165 degrees C). Bake until eggs are solid, approximately 60 minutes.