Preheat oven to 375°F (190°C) and grease a 9x13-inch baking dish.
In a large skillet over medium-high heat, heat olive oil and cook the turkey sausage until browned and crumbled, about 8 minutes.
Add the diced onion and bell pepper to the skillet and sauté for an additional 5 minutes until vegetables are softened.
In a large mixing bowl or blender, combine the eggs, cottage cheese, garlic powder, salt, and pepper. Blend or whisk until the cottage cheese curds are smooth and fully integrated.
Stir the chopped spinach, cooked sausage mixture, and 1 cup of the shredded cheddar cheese into the egg mixture.
Pour the combined mixture into the prepared baking dish, ensuring the ingredients are evenly distributed.
Sprinkle the remaining 0.5 cup of shredded cheddar cheese over the top of the casserole.
Bake for 35 to 45 minutes until the eggs are set in the center and the edges are golden brown.
Allow the casserole to rest for 10 minutes before slicing into 8 portions.