1-Preparing the Bread: The first step in creating the perfect texture for your casserole is preparing the bread cubes. Cut 12 slices of thick bread into cubes to yield approximately 14 cups. These cubes need to be dried slightly to prevent the final dish from becoming too soggy. You can accomplish this by leaving the cubes out on a baking sheet overnight or warming them in a 300°F oven for about 10 minutes. This drying process allows the bread to better absorb the egg mixture without becoming mushy.

2-Assembling the Casserole: Grease a 9×13 inch baking dish thoroughly to prevent sticking. Build the casserole in two distinct layers for even distribution of ingredients. Start with half the bread cubes distributed evenly across the bottom of the dish. Follow this with half the crumbled bacon or diced ham, the sliced green onions, diced red bell pepper, and half the shredded cheese. Repeat these layers with the remaining ingredients, finishing with cheese on top.

3-Creating the Custard: In a large mixing bowl, whisk together 6 large eggs, 3 cups of milk, ½ teaspoon of dry mustard powder, ½ teaspoon of salt, and ½ teaspoon of black pepper until fully blended. This custard mixture is the liquid gold that will transform your layered ingredients into a cohesive, delicious breakfast dish. Whisk thoroughly to ensure the seasonings are evenly distributed throughout the liquid.

4-Soaking Overnight: Pour the egg custard mixture evenly over the layered ingredients in the baking dish. Use a spoon or your hands to gently press down on the bread to ensure all pieces get moistened by the liquid. Cover the dish with foil or plastic wrap and refrigerate for at least 3 hours, though overnight is best. This soaking time allows the bread to fully absorb the custard, flavors to meld together, and ensures the final texture will be perfectly set rather than dry or watery.

5-Baking Instructions: The next morning, remove the casserole from the refrigerator and let it sit at room temperature while you preheat the oven to 350°F. This helps prevent thermal shock that could cause the glass dish to crack and ensures more even baking. Bake the casserole covered with foil for 45 to 55 minutes. If you’ve doubled the recipe, expect a longer baking time. The casserole is done when a knife inserted in the center comes out clean, indicating the custard has set.

6-Adding the Final Touch: For those who enjoy a crispy top, remove the foil for the last few minutes of baking or place the casserole under the broiler for about 3 minutes until golden and bubbly. Watch closely to prevent burning. Let the dish rest for 5-10 minutes before cutting and serving. This resting period allows the casserole to set properly, making it easier to serve and ensuring each slice holds its shape.