Spray a 9×13 casserole dish with non-stick spray. Preheat the oven to 350ºF.
In a large skillet over medium heat, brown the sausage. Use a spatula or wooden spoon to break up the sausage into smaller pieces as it cooks. Spoon the browned sausage evenly into prepared casserole dish. Set aside.
To the same large skillet, sauté the spinach and peppers until the vegetables are tender, about 5 minutes. Add the cooked vegetable mixture to the sausage in casserole dish. Stir together to distribute the vegetables evenly. Set aside.
In a medium-size bowl, whisk together the eggs, heavy cream, and 1 cup of the shredded cheese. Season with the garlic powder, black pepper, and salt.
Pour egg mixture evenly over sausage and vegetable mixture. Stir to combine. Sprinkle with remaining 1/2 cup of shredded cheese.
Bake for approximately 30-40 minutes, or until the eggs are set and the edges start to brown. Allow to cool at least 10 minutes before serving.