In a large skillet, simmer the Arborio rice and warm broth over medium heat, adding the liquid one cup at a time. Stir frequently until the rice is tender and the mixture is highly creamy and thick.

Remove from heat, stir in the grated Parmesan cheese, and let it cool slightly before mixing in one beaten egg. Spread the cooked risotto onto a parchment-lined baking sheet and chill in the refrigerator for at least 2 hours.

Once chilled, scoop up about 2 tablespoons (30g) of the mixture into your wet hands. Flatten it slightly, place a cube of mozzarella cheese in the center, and fold the edges of the rice over the cheese, rolling it tightly into a smooth sphere.

Preheat your oven to 400°F (200°C) and line a clean baking sheet with fresh parchment paper. Set up three shallow bowls: one with all-purpose flour, one with two whisked eggs, and one with Panko breadcrumbs mixed with the olive oil.

Gently roll each stuffed rice ball in the flour, dip it fully into the beaten eggs, and then roll it thoroughly in the oiled Panko breadcrumbs. Press the crumbs gently into the surface.

Place the coated balls on the prepared baking sheet, spacing them 1 inch apart. Bake in the preheated oven for 20-25 minutes until a deep golden-brown crust has formed.

Remove from the oven and let rest for 3 minutes. Transfer to a rustic stoneware bowl, sprinkle with finely chopped fresh parsley, and serve immediately with a small bowl of marinara sauce.