01 - Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
02 - Cook macaroni in salted boiling water until al dente. Drain and set aside.
03 - In a small saucepan, melt butter over medium heat. Stir in flour and cook for 30 seconds. Gradually whisk in milk, cooking until slightly thickened (about 2 minutes). Add cheddar cheese, stirring until melted and smooth. Season with salt and pepper.
04 - Combine cooked macaroni with the cheese sauce. Let cool for 10 minutes to firm.
05 - In a large bowl, mix ground beef, breadcrumbs, Parmesan, egg, milk, garlic, salt, pepper, oregano, and basil until just combined. Avoid overmixing.
06 - Divide meat mixture into 12 equal portions. Flatten each into a disc. Place 1 tablespoon of mac and cheese in the center and gently wrap the meat around, sealing well to form a ball.
07 - Arrange stuffed meatballs on the prepared baking sheet.
08 - Bake for 20 minutes.
09 - Remove from oven, spoon marinara sauce over meatballs, and sprinkle with mozzarella if using. Return to oven and bake for an additional 8–10 minutes, until cheese is bubbly and meatballs are cooked through.
10 - Garnish with chopped parsley and serve hot.