📖 Instructions

1. **Prepare Your Ingredients (Night Before):** First, you'll want to get all your ingredients prepped. If using raw sausage, heat a large skillet over medium-high heat. Add the sausage and cook, breaking it up with a spoon, until it's browned and cooked through. Drain any excess grease and set aside to cool slightly. If you're using pre-cooked sausage or bacon, just chop it up.
2. **Sauté Aromatics (Optional, but Recommended!):** In the same skillet (or a clean one), if you want to add some extra flavor, sauté any chopped onions, bell peppers, or mushrooms until they're soft. This really builds a nice flavor base. Don't skip this if you have the time!
3. **Prepare the Bread Base:** Lightly grease a 9x13-inch baking dish. Tear or cut your bread into 1-inch cubes. You can use stale bread or fresh bread, it doesn't matter much. Arrange these bread cubes in an even layer at the bottom of the prepared baking dish. This is going to be our fluffy base.
4. **Layer the Savory Fillings:** Sprinkle the cooked sausage (or bacon, or ham) evenly over the bread cubes. If you've sautéed any veggies, add those next. Then, generously sprinkle your shredded cheese over the meat and veggies. You want a good, even layer of cheese.
5. **Whisk the Egg Mixture:** In a large mixing bowl, crack all your eggs. Add the milk, Dijon mustard (trust me on this one, it adds a subtle tang!), salt, black pepper, and any other seasonings you like (a pinch of garlic powder or onion powder is great here). Whisk everything together really well until the egg mixture is smooth and slightly frothy. You don't want any streaks of egg white.
6. **Pour and Press:** Carefully pour the egg mixture evenly over the layers in your baking dish. Make sure all the bread cubes are thoroughly moistened. Use a spatula or the back of a spoon to gently press down on the bread and other ingredients, ensuring they are submerged in the egg mixture. This helps the casserole soak up all that eggy goodness overnight.
7. **Cover and Chill:** Cover the baking dish tightly with plastic wrap. Place it in the refrigerator and let it chill overnight, or for at least 8 hours. This resting time is crucial—it allows the bread to soak up the egg mixture and all the flavors to truly mingle.
8. **Preheat Oven (Morning Of):** The next morning, take the casserole out of the refrigerator about 30 minutes before you plan to bake it to let it come closer to room temperature. While it's resting, preheat your oven to 375°F (190°C).
9. **Bake to Golden Perfection:** Remove the plastic wrap from the casserole. Place the baking dish in the preheated oven. Bake for 45-60 minutes, or until the casserole is golden brown on top, puffed up, and a knife inserted into the center comes out clean. If the top starts to brown too quickly, you can loosely tent it with aluminum foil.
10. **Rest and Serve:** Once baked, remove the casserole from the oven. Let it rest for about 5-10 minutes before slicing and serving. This resting period allows the casserole to set up nicely and makes for cleaner slices. Serve warm with your favorite toppings like salsa, hot sauce, sour cream, or fresh chives. Enjoy your wonderfully stress-free breakfast!