Preheat oven to 325 degrees.
Cut bacon into small strips. Cook bacon until crisp and drain on a paper towel, reserving 2 tablespoons of the bacon grease in the pan. (Save the remaining bacon grease in a covered container in the refrigerator for future uses -- to season vegetables, for cornbread, or anytime you want to add some great bacon taste to something.).
Using the same pan that you cooked the bacon in with the 2 tablespoons of bacon grease, saute the diced onions until tender. Add the diced green pepper and saute for a couple of minutes. Set the peppers and onions aside and allow to cool a little.
Have the plum tomatoes (I like Roma ) diced and ready. Set aside.
Spray a 13x9x2-inch glass baking dish with a non-stick cooking spray, like Pam. Line the bottom of the baking dish with the seasoned croutons. You want them in a single layer. This may take a little more or less than 3 cups. Sprinkle the grated Velveeta cheese all over the top of the croutons.
Whisk together the eggs and sour cream until well mixed. Add the cooked peppers and onions, salt, pepper, mustard and milk to the egg mixture. Mix well. Pour on top of the croutons and cheese in the baking dish.
Sprinkle the diced tomatoes on top. Then, sprinkle the cooked bacon on top,.
Bake 50 minutes to an hour or until center is set. Enjoy!