If you already have cooked risotto, make sure to let it sit at room temperature for about 10 minutes. If you are making a fresh one, allow it to cool down completely before shaping suppli.
Line a tray or a baking sheet with a parchment paper.
In a three separate shallow dishes, add beaten eggs, flour and breadcrumbs.
Take a small amount of risotto (about 2 Tablespoons) in your hand and flatten it slightly. Place one or two cubes of mozzarella in the center.
Cover the mozzarella with the risotto, ensuring the cheese is completely enclosed. You can add more rice if needed to cover the cheese. Shape suppli into an oval (or a ball).
Roll shaped suppli in the flour, shaking off any excess flour. Next, dip it into beaten eggs. Lastly, roll it gently into breadcrumbs until fully coated. Place breaded suppli on a prepared tray. Repeat the process with the rest of the rice.
Chill breaded suppli in the fridge for at least 20 minutes. Chilling helps to hold the shape better while frying.
In a deep saucepan or deep fryer, heat vegetable oil to around 350°F. *see notes below how to air fry or bake them.
Carefully add chilled suppli into hot oil, 3-4 at a time, to avoid overcrowding the pan. Fry them for about 3-4 minutes or until they turn golden brown.
Use a slotten spoon to remove suppli from the hot oil and place them on a plate lined with some paper towels to absorb any excess oil.
Serve them while they are hot and fresh with some marinara sauce for dipping.