In a large mixing bowl, combine ground beef or pork, egg, breadcrumbs, grated Parmesan, parsley, minced garlic, salt, and pepper. Mix gently until just combined, then shape into 20-24 meatballs.

Heat olive oil in a large skillet over medium heat. Add the meatballs and brown on all sides for about 6-8 minutes. Transfer to a plate.

In the same skillet, reduce heat and add butter, letting it melt. Stir in minced garlic and cook for 1-2 minutes. Add red pepper flakes and lemon juice.

Return meatballs to skillet and simmer in the garlic butter sauce for 5-7 minutes until cooked through.

Boil water in a pot, add salt, and cook linguine according to package directions until al dente. Reserve ½ cup pasta water before draining.

In a separate saucepan, melt additional butter, stir in heavy cream, and heat through. Add grated Parmesan cheese until creamy. Adjust thickness with reserved pasta water.

Combine drained linguine with the creamy sauce, toss to coat. Serve linguine, topped with meatballs and extra garlic butter sauce.