Preheat oven to 350 degrees F. Move oven rack to the second highest position from the top.
Lightly spray a 10-inch oven-safe skillet with cooking spray.
In a medium bowl, whisk eggs, cottage cheese, Pecorino Romano, spinach, salt, and pepper. Set aside.
Add sausage to the skillet, breaking it into small pieces with a wooden spoon over medium heat and cook until browned and cooked through, about 4 minutes.
Add the egg mixture to the skillet and cook for 1 minute to let the bottom set.
Bake in the oven until the top is set, about 16 to 18 minutes.
With a spatula, carefully slide the frittata out of the skillet onto a cutting board and cut into 4 wedges.
Serve with salad and whole grain bread, if desired.
Notes
This frittata is versatile and perfect for meal prep. You can substitute sausage with turkey or omit for a vegetarian option. Enjoy warm or cold!