Preheat your oven to 350°F and butter a 9x13-inch baking dish generously. Distribute the bread cubes evenly across the bottom of the prepared dish, creating a sturdy foundation for your egg mixture.
Heat 1 tbsp butter in a large skillet over medium heat and sauté the diced onions and bell peppers until softened, about 4 minutes. Add the diced mushrooms and cooked chicken breast, stirring occasionally until everything is heated through and fragrant.
In a large mixing bowl, whisk together 8 eggs and 1 cup whole milk until completely combined and slightly frothy. Season the egg mixture with salt, black pepper, garlic powder, and paprika, stirring well to distribute the spices evenly throughout.
Pour the sautéed vegetables and chicken over the bread cubes in your baking dish. Spread them in an even layer to ensure consistent cooking and flavor distribution throughout the cozy savory egg bake brunch recipe.
Pour the whisked egg mixture over the vegetables and bread, then sprinkle shredded cheddar cheese across the top. Bake for 35-40 minutes until the center is set and the top is lightly golden, then remove and let rest for 5 minutes before serving.
Garnish with fresh parsley and diced tomatoes just before presenting to your guests. These final touches add color and freshness that elevate the entire presentation of your savory egg bake.