Preheat the oven to 375 degrees F. Blanch the spinach in water. Drain and chop. Mix the ricotta cheese with the spinach. Add the Parmesan and the flour. Mix well. Add a pinch of salt and pepper. Take 1 tablespoon full of the ricotta mixture and form small balls with your hand (about 1/2 inch.) Place in a casserole dish.
Add some tomato sauce over the ricotta-spinach balls. Sprinkle some Parmesan over and cook for 10 minutes.