Heat until hot but not smoking; add onions.
Toss to coat with oil. Turn heat down to medium and cook until onions are soft and browned, about 25 minutes. Season with salt and pepper to taste.
Prepare a ricotta cheese mixture. Mix ricotta cheese, chopped rosemary, eggs, half the grated Parmesan and salt and pepper to taste.
Make a spinach Mornay sauce. Melt butter in a saucepan, add flour and stir. Add milk and stir until it comes to a boil. Add the rest of the grated Parmesan, the nutmeg and the defrosted spinach.
Season with salt and pepper.
18 Keto Recipes - Low Carb Super Comp - Well Done