Preheat oven to 375°F and line a rimmed baking sheet with aluminum foil. Spray with nonstick spray and set aside.
Heat a medium skillet over medium heat. Add the oil and onion and cook until onion is tender and translucent. Remove from the heat and add the garlic. Stir and set aside to cool a little.
1 tablespoon olive oil, ½ cup diced onion, 1 clove garlic
In a large mixing bowl, add the breadcrumbs, sautéed vegetables, eggs, Parmesan, salt, black pepper, herbs, and half-and-half. Stir until combined.
1½ cups breadcrumbs, 2 large eggs, ¼ cup freshly grated Parmesan cheese, 1½ teaspoons kosher salt, ½ teaspoon freshly ground black pepper, 1 teaspoon Herbs de Provence, ¼ cup half-and-half
Add ground turkey and mix together until incorporated.
2 pounds ground turkey
If possible, use a 2-inch cookie portion scoop to make the filled balls. If a scoop isn’t available, form the meatball with your hands.
Spray the scoop (or your hands) with nonstick spray when you begin and then as needed.
Scoop a 2-inch round ball of meat mixture into the scoop and push a mozzarella ball into the middle. (Be careful not to push the mozzarella ball too far into the meat – try to keep it in the middle of the meatball.)
8 ounces Mozzarella Ciliegine
Cover the top of the mozzarella ball with the meat mixture that squeezes out when the cheese ball is pushed into the center. Be sure the mozzarella ball is evenly surrounded by the meatball mixture. Gently round the meatball with your hands and place the ball on the prepared cooking sheet.
Repeat until all the meatballs are made, placing them about 1½-inches apart.
Bake the meatballs at 375°F for 20-25 minutes, or until brown and cooked through to 165°F.
Serve with your favorite dipping or marinara sauce.