Preheat the oven to 375F (191 C). Generously grease a 9x13 inch baking pan or similar size( about 3 quart) casserole dish.
Layer the bread pieces, chopped bell pepper, tomatoes, and bacon into dish.
Whisk the eggs, milk, cheese, mustard, cream cheese, salt, and pepper together in a large bowl. Pour evenly over bread mixture.
Bake for 40-50 minutes or until center is set and edges are golden brown. Remove from the oven and allow to cool for 10 minutes before slicing, and serving.
Cover leftover casserole tightly and refrigerate for up to 1 week.