Polenta and Meatballs

Ingredients

• Meatballs
• 1 tablespoon extra-virgin olive oil
• 1 sweet onion, fined chopped
• 2 garlic cloves, finely chopped
• ¼ cup grated Parmesan cheese, plus more for serving
• ½ cup chopped fresh parsley, plus more for serving
• ½ teaspoon dried oregano
• 1 large egg
• 1 pound ground beef
• ¾ cup panko bread crumbs
• Kosher salt and freshly ground black pepper
• 2½ cups jarred marinara sauce
• Polenta
• 1 cup whole milk
• 1 cup polenta (not instant)
• 3 tablespoons unsalted butter