Preheat the oven to 180 ° C. Mix rice, broth and white wine in a casserole dish (2 1/2 l contents), close it tightly with aluminum foil or a lid. Cook in the oven for 40 minutes, until the liquid is almost completely absorbed and the rice is firm to the bite.
Chop the onion and fry in a pan with a little oil. Add the frozen spinach leaves to the pan and heat until thawed. Season with salt, pepper and nutmeg. Cut the feta cheese into small pieces.
Take the risotto out of the oven. Fold in the parmesan, spinach, onions and feta cheese. Season with salt and pepper as needed. Let it steep for a few minutes and serve.