For Pumpkin Risotto (ahead of time):

1. Prepare the base: Heat the butter in a pan over medium heat and sauté the onion for 2-3 minutes until soft. Add the garlic and cook for another 2-3 minutes, ensuring the onions don’t brown.
2. Cook the rice: Add the arborio rice to the pan and stir to coat in the butter. Add the wine or vermouth and cook until absorbed. Gradually add the stock, about ½ to 1 cup at a time, stirring occasionally, until the liquid is absorbed before adding more. Continue this process until the rice is fully cooked (about 20 minutes).
3. Flavor the risotto: Once the rice is cooked and creamy, stir in the pumpkin puree, parmesan, and nutmeg (if using). Season with salt and pepper to taste. Let the risotto cool, then refrigerate it for at least a couple of hours or overnight.

For Arancini:

1. Preheat the oven: Preheat the oven to 375°F (190°C). Lightly oil a baking sheet.
2. Prepare the filling: Take slightly heaped tablespoonfuls of the chilled risotto mixture and flatten it in your hand. Place a cube of mozzarella in the center, fold the risotto around the cheese, and roll into a ball. Repeat with the remaining risotto and mozzarella cubes.
3. Coat the arancini: Set up a breading station with flour, beaten eggs, and breadcrumbs in separate bowls. Roll each risotto ball first in the flour, then dip it in the egg, and finally coat it with breadcrumbs. Shake off any excess after each step.
4. Bake the arancini: Place the coated arancini on the prepared baking sheet. Bake in the preheated oven for 8-10 minutes until the breadcrumbs are golden and crisp.

Serve: Serve the arancini warm, optionally with marinara sauce for dipping. Enjoy as a comforting snack or appetizer!