Step 1: In a bowl, combine ground beef, egg, 10g of grated Parmesan, salt, and black pepper. Mix thoroughly but gently to avoid overworking the meat. Form into 4-5 evenly sized meatballs.

Step 2: In a large skillet, melt 3g of butter over medium-high heat until shimmering. Carefully place meatballs in the skillet, ensuring not to overcrowd. Sear meatballs for 3-4 minutes per side until deeply browned and a crust forms. Remove meatballs and set aside.

Step 3: Reduce heat to medium. Add remaining 2g butter to the skillet, scraping up any browned bits. Whisk in heavy cream and beef broth. Bring to a gentle simmer. Gradually whisk in remaining 20g Parmesan cheese, stirring constantly until sauce is smooth and slightly thickened, about 3-5 minutes. Adjust seasoning as needed.

Step 4: Return meatballs to the sauce, coating them evenly. Simmer for 5-7 minutes, turning occasionally, until meatballs are cooked through and the sauce has reduced to a luscious consistency. Serve immediately, ensuring the sauce is perfectly emulsified.