Melt 50 g butter and two tablespoons of extra-virgin olive oil in a high-sided pan. Add the peeled and chopped onion, the ground beef and let it brown for five minutes. Deglaze with white wine, let it evaporate and add the tomato puree. Add salt and pepper to taste and cook over a medium heat for about 30 minutes until the sauce has thickened.

Add the rice and cook it, adding the meat stock one ladle at a time. Turn off the flame, stir in the remaining butter and, when the rice has cooled, add two beaten eggs. Mix well and pour the mixture into a bowl to cool completely.

Cut the mild Provolone Valpadana P.D.O. into cubes. Form the croquettes by taking about 100 g of rice mixture, being careful to place some cheese cubes in the middle and give them an oval shape.

Dip the croquettes in the two remaining well-beaten eggs and finally in the breadcrumbs.

Deep-fry them in plenty of hot peanut oil. Drain on a sheet of absorbent paper and serve.