- Preheat the oven to 400 degrees F (200 degrees C).
- Heat 1 tablespoon olive oil in a saucepan over medium heat. Add onion and 2 cloves garlic; cook and stir until onion is soft, about 5 minutes.
- Place beef in a large bowl. Add onion-garlic mixture, parsley, egg, bread crumbs, and 1 large handful of fontina cheese, reserving the rest for topping. Season with salt, pepper, and cayenne. Mix by hand until just combined. Scoop meat mixture into 24 mini muffin cups; meatballs need not be perfectly round.
- Bake in the preheated oven until no longer pink in the centers, about 12 minutes. Leave oven on. Let meatballs cool briefly while you make the garlic butter.
- Melt butter in a saucepan over medium heat. Add remaining minced garlic once butter starts to bubble; stir, then immediately remove from heat. Stir well and set aside.
- Line a rimmed baking sheet with foil; coat foil with remaining olive oil. Transfer rolls, still attached, to the baking sheet. Cut a hole in the top of each roll, about 2/3 of the way down. Brush garlic butter over the insides and outsides of the rolls.
- Bake until golden brown, about 8 minutes. Pour about 1 tablespoon tomato sauce into each hole. Stuff meatballs into the holes. Top each roll with a spoonful of tomato sauce and remaining fontina cheese. Sprinkle Parmesan cheese on top.
- Continue baking until cheese is melted, 12 to 15 minutes. Garnish with more parsley. Let rolls sit for 5 to 10 minutes to firm up; transfer to a serving platter.
% Daily Value *
Total Fat: 15 %
Cholesterol: 26 %
Sodium: 26 %
Potassium: 5 %
Total Carbohydrates: 15 %
Dietary Fiber: 10 %
Protein: 42 %