Zucchini Stuffed with Ricotta (Zucchine Ripiene con Ricotta)

Ingredients

• 6 medium zucchini (about 2 lbs.), halved lengthwise
• 7 tbsp. extra-virgin olive oil
• 3 cloves garlic, finely chopped
• 1 yellow onion, finely chopped
• 2 medium tomatoes, cored, seeded, and chopped
• 2 cups homemade or store-bought ricotta
• 3⁄4 cup grated pecorino
• 3⁄4 cup fresh bread crumbs
• 3 tbsp. finely chopped flat-leaf parsley leaves
• 2 tsp. dried mint, crumbled
• 2 tsp. chopped fresh oregano
• 2 egg yolks, beaten
• Kosher salt and freshly ground black pepper, to taste