Preheat oven to 375°F (190°C) and grease a 9x13 inch baking dish with non-stick cooking spray.
In a large skillet over medium-high heat, brown the turkey sausage until fully cooked and no pink remains. Drain any excess liquid.
Place the cottage cheese and eggs into a blender. Process on medium speed until the mixture is completely smooth and homogeneous.
Distribute the cooked turkey sausage, diced bell peppers, chopped onions, and spinach evenly across the bottom of the prepared baking dish.
Pour the blended egg and cottage cheese mixture over the dry ingredients in the dish. Use a spatula to gently stir and ensure even distribution.
Sprinkle garlic powder, salt, and black pepper over the top and incorporate slightly.
Evenly distribute the shredded mozzarella cheese over the surface of the casserole.
Bake for 35 to 40 minutes, or until the internal temperature reaches 160°F (71°C) and the center is set and no longer jiggles.
Remove from the oven and allow the casserole to rest for 10 minutes to firm up before slicing into 8 equal portions.