01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish.
02 - In a large skillet over medium heat, cook sausage until browned and cooked through, breaking up with a spoon. Drain excess fat.
03 - Add diced onion and red bell pepper to the skillet. Sauté 3-4 minutes until softened. Stir in spinach and cook until wilted, about 1 minute. Remove from heat.
04 - In a large bowl, whisk together eggs, milk, salt, pepper, garlic powder, and paprika until combined.
05 - Spread cubed bread evenly in the prepared baking dish. Layer sausage and vegetable mixture on top. Sprinkle shredded cheese evenly over all.
06 - Pour egg mixture evenly over the layered ingredients, pressing gently to help bread absorb the liquid.
07 - Bake uncovered for 40-45 minutes, until the center is set and the top is golden brown.
08 - Let cool for 5-10 minutes. Garnish with fresh herbs if desired, then slice and serve warm.