Peel Potatoes and cut into small cubes. Cook in salted water until soft. Drain and half-mash lightly.
Heat 1/2 tablespoon Oil in a frying pan and cook finely chopped Onion and Garlic until tender. Season with Salt and Pepper.
Defrost the frozen Spinach pieces and remove excess liquid. If you use Fresh Spinach, you can cook it with the Onion.
Combine half-mashed Potatoes, Onion mixture, Spinach and Ricotta. Add some more Salt and Pepper to taste only if requires. Be careful as Ricotta can be quite salty.
Oil the base and side of ramekins or a baking dish and spoon the mixture. Top with plenty of grated Parmesan Cheese. Bake for 20 minutes or until cheese is melted and golden.
Note: It can be easily removed from the ramekins, so that you can place the individual gratin on serving plates.
