Bring a large pot of salted water to a rolling boil. Add the elbow macaroni and cook for 9-10 minutes, until al dente. Stir in a knob of butter until it melts, coating the macaroni.

In a separate saucepan, warm the evaporated milk over medium heat. Gradually add shredded cheddar and Colby Jack cheeses, stirring until melted and creamy. Season with salt and pepper.

In a skillet, heat oil over medium heat. Add ground beef and cook until browned. Mix in onions and bell peppers, sauté until softened. Stir in diced tomatoes and pasta sauce, simmer for 5 minutes.

Preheat oven to 350°F. In a greased baking dish, layer macaroni, followed by meat sauce. Repeat layers, finishing with macaroni and sprinkle remaining cheese on top.

Bake uncovered for 15 minutes, then broil for 2-3 minutes until top is crispy. Watch closely to avoid burning.

Let the lasagna rest for 10 minutes before serving.