In a large mixing bowl, combine the ground beef, egg, breadcrumbs, grated Parmesan cheese, chopped parsley, minced garlic, salt, and black pepper. Mix gently until just combined. Form into 1-inch meatballs (20-24 total).

Heat olive oil in a large skillet over medium heat. Add the meatballs, browning on all sides (6-8 minutes). Remove meatballs from skillet.

In the same skillet, reduce heat to low. Add unsalted butter and let it melt, then add minced garlic and red pepper flakes, cooking for 1-2 minutes. Add lemon juice and return meatballs to the skillet, simmering for 5-7 minutes.

Boil salted water in a large pot, and cook linguine until al dente (8-10 minutes). Reserve 1/2 cup of pasta water before draining.

In a separate pan, melt additional butter, then add heavy cream. Mix in Parmesan until melted, creating a sauce.

Toss linguine with sauce, then add meatballs, ensuring each is covered in the sauce. Adjust thickness with reserved pasta water if necessary.

Serve by plating linguine topped with meatballs and drizzled with sauce. Garnish with parsley and extra Parmesan.