What You Need
In a medium bowl, using your hands combine ground beef, parmesan, panko, parsley, basil, milk, egg, half of the garlic, 1 teaspoon salt, and ¼ teaspoon pepper. Roll mixture into mini meatballs, about 1 level tablespoon each, and arrange in a single layer on a plate. It should make about 40 mini meatballs.
Heat 2 tablespoons of the oil in a 3.3 QT Hexclad Deep Sauté Pan over medium-high. Add meatballs in a single layer and cook, turning a few times, until golden all over, 5 to 7 minutes total. Remove meatballs to plate.
Discard excess oil in pan and return to medium heat. Add remaining tablespoon oil and remaining half of garlic. Cook, stirring, until garlic is fragrant and lightly toasted, about 30 seconds. Add tomatoes, ½ cup water, ½ teaspoon salt, sugar, and basil sprig. Bring to a simmer, then reduce heat to medium-low and simmer partially covered until thickened and full flavored, about 25 minutes. Season with salt and pepper.
Meanwhile, fill a Hexclad 5 QT Dutch Oven with water and bring to a boil. Season water generously with salt and cook pasta according to package directions until al dente. Drain, reserving 1 cup pasta water and set pasta aside.
Remove and discard the basil from the marinara and add butter, stirring until melted and combined. Using a spoon or ladle, remove meatballs and about half of the sauce to a large heatproof bowl. Increase heat to medium-high and add pasta to remaining sauce in pan, tossing to coat and adding pasta water a tablespoon or so at a time, if necessary to thin sauce. Serve topped with reserved meatballs and sauce and sprinkled with parmesan cheese.