Preheat your oven to 350°F (175˚C) and move oven rack to high position (I use second from top).
Lightly spray a 10-inch oven-safe pan with olive oil spray
In a medium bowl, whisk eggs, cottage cheese, parmesan cheese, spinach, salt and pepper. Set aside and place your skillet or cooktop-safe dish on a medium heat.
Add sausage to a skillet, breaking it up in small pieces with a wooden spoon over medium heat and cook until browned and cooked through - about 4 or 5 minutes.
Add your egg and cheese mixture to the pan and cook 1 minute to let the bottom set.
Move the cooked mixture into your baking dish (this can be a bit tricky and is why a cooktop-safe dish is great) and bake in the oven until the top is set, about 15 to 20 minutes depending on your oven.
Once out of the oven, slice the frittata into pieces and slide them out with a spatula, or just serve direct from the dish.
Enjoy on its own, or serve with a side of garden or Greek salad if desired!