Cook the pasta in salted water until al dente. Drain and set aside.
Prepare the meat sauce by sautéing the onion, garlic, and leek in a pan with a little oil. Add the minced meat and cook until browned.
Add the red pepper and tomatoes, season with salt and black pepper, and let simmer for 10 minutes.
Make the béchamel sauce by melting butter in a saucepan, whisking in the flour, then slowly adding milk while stirring until smooth and thick.
Combine everything in a baking dish: layer the pasta, meat sauce, and béchamel, then top with grated mozzarella.
Bake at 375°F (190°C) for 20-25 minutes until golden and bubbling.
Serve warm and enjoy a comforting, cheesy, and hearty Italian-style meal!