In a large pot, melt the butter over medium heat. Add the chopped onion and sauté until soft and translucent.
Add the Arborio rice and stir well, making sure the grains are coated with the melted butter.
Gradually add the warm chicken broth, one ladle at a time, stirring frequently. Allow each addition to absorb before adding more.
Continue cooking for about 18–20 minutes, until the rice is creamy and tender.
Stir in the grated Parmesan cheese and season with salt and pepper. Spread the risotto onto a shallow tray and allow it to cool completely.
Take a spoonful of cooled risotto and flatten it slightly in your palm. Place a cube of mozzarella or cheddar in the center.
Gently shape the rice around the cheese to form a ball, making sure the cheese is completely covered. Repeat with the remaining risotto.
Dip each rice ball into the beaten eggs, then roll in Panko breadcrumbs until evenly coated.
Heat olive oil in a deep pot to 350°F. Fry the arancini in batches for about 3–4 minutes, turning as needed, until golden brown and crispy.
Remove with a slotted spoon and drain on paper towels.
Let cool slightly and serve warm with marinara sauce for dipping. Enjoy that delicious cheesy center!
