Mix the ground beef, breadcrumbs, Parmesan cheese, egg, minced garlic, oregano, salt, and black pepper in a large bowl until evenly combined. Shape the mixture into a loaf and place it in a loaf pan.
Bake the meatloaf at 350°F for 45 minutes. While it bakes, stir the tomato sauce and brown sugar together in a small saucepan. Heat the sauce over medium-low heat until the brown sugar dissolves, then keep it warm.
Brush both sides of the polenta rounds with olive oil. Place them on a baking sheet and bake for the last 15 minutes alongside the meatloaf until the edges turn golden.
Remove the meatloaf from the oven and let it rest for 5 minutes. Slice it and serve the pieces with the warm tomato-brown sugar sauce spooned over the top. Add the polenta rounds on the side and finish with a few fresh basil leaves.