Bring a large pot of well-salted water to a rolling boil. Add the macaroni and cook until al dente, about 8-10 minutes, stirring occasionally. Before draining, reserve 125ml of pasta water in a measuring cup.

While pasta cooks, melt 1-2 tablespoons butter in a large skillet over medium heat until bubbling. Add minced garlic, chopped onion, and bell peppers. Sauté for 4-5 minutes, stirring frequently, until vegetables become tender and onions turn translucent.

Crumble in the lean ground beef, breaking it apart with a wooden spoon as it cooks. Brown for 5-7 minutes until no pink remains. Drain any excess fat if needed.

Season the beef mixture generously with salt, pepper, paprika, and chili flakes to taste.

Reduce heat to low. Stir in light cream cheese, shredded mozzarella, and cheese slices. Keep stirring constantly until everything melts together into a smooth, velvety sauce, about 3-4 minutes. Be patient during this step to prevent graininess.

Add the cooked macaroni along with the reserved pasta water to the skillet. Mix until all pasta is evenly coated in the creamy sauce. If the sauce appears too thick, gradually add more pasta water until reaching desired consistency.

Taste and adjust seasoning as needed. Garnish with fresh parsley if desired and serve immediately.