Preheat your oven to 350°F (175°C) and generously coat a 9x13-inch baking dish with non-stick cooking spray.
In a large skillet over medium-high heat, cook the breakfast sausage, breaking it up with a wooden spoon, until it is browned and no longer pink, about 8-10 minutes. Use a slotted spoon to transfer the cooked sausage to a paper towel-lined plate to drain excess grease.
In the same skillet with 1 tablespoon of the reserved sausage drippings, sauté the chopped onion and red bell pepper over medium heat until they are softened, about 5-7 minutes.
Spread the thawed hash browns evenly across the bottom of the prepared baking dish. Layer the cooked sausage and the sautéed onion and pepper mixture on top, then sprinkle with the shredded cheddar cheese.
In a large bowl, vigorously whisk together the eggs, milk, heavy cream, salt, black pepper, garlic powder, and paprika until the mixture is completely smooth and uniform in color.
Carefully pour the egg mixture evenly over the layers in the baking dish, ensuring it soaks through to the bottom. Gently shake the dish to help settle everything.
Bake uncovered for 50-60 minutes, or until the center is fully set, the edges are golden brown, and a knife inserted into the center comes out clean. Let the bake rest for 10 minutes before slicing and serving.
