Little Stuffed Zucchinis

Name: Little Stuffed Zucchinis
Ingredients: 4 small round zucchini; 4 tablespoons olive oil, plus 4 teaspoons; 1 small yellow onion, minced; 6 small cloves garlic, minced; 1/2 teaspoon chili flakes; Kosher salt; Freshly ground black pepper; 4 tablespoons chopped fresh basil; 2 teaspoons chopped fresh mint; 2 cups very roughly ground homemade breadcrumbs (made from running cubes of day-old bread through the food processor); 20 walnuts halves, well chopped; 1 cup coarsely grated pecorino romano