In a large mixing bowl, combine ground beef, egg, breadcrumbs, grated Parmesan, chopped parsley, minced garlic, salt, and black pepper. Mix gently until just combined, then shape into 1-inch meatballs and place on a baking sheet.

Heat 2 tablespoons of olive oil in a skillet over medium heat. Once shimmering, add meatballs in a single layer. Sear for 6–8 minutes, turning occasionally until browned on all sides.

In the same skillet, reduce heat to low and add 4 tablespoons of unsalted butter, allowing it to melt. Add minced garlic and red pepper flakes, sauté for 1–2 minutes.

Return browned meatballs to the skillet, coating in garlic butter sauce. Cover and simmer for 5–7 minutes until fully cooked at 160°F.

While meatballs simmer, cook linguine according to package instructions, usually about 8–10 minutes.

In a separate saucepan, melt another tablespoon of butter over medium heat. Add 1/2 cup of heavy cream and simmer, then stir in reserved pasta water and grated Parmesan until creamy.

To serve, twirl creamy linguine onto plates, top with meatballs, drizzle with garlic butter sauce, and garnish with parsley and Parmesan.