Brown the onion with a little butter in a pan, add the rice and stir well. Gradually add the broth to the rice until almost fully cooked, ensuring it remains very soft all the while. In the meantime, toast the slices of bread with a little butter and thinly slice the fontina PDO. Layer a deep baking tray with bread, followed by rice and then fontina PDO, until you finish all the ingredients. Add the cinnamon aroma, remaining melted butter and a little butter to soften. Bake in the oven at 200° for 5 minutes. Serve immediately.