Start by bringing a large pot of salted water to a rolling boil over high heat. Add elbow macaroni and cook until al dente, about 7-8 minutes, stirring occasionally. Once done, drain the macaroni in a colander and set it aside.

In a large saucepan, melt 4 tablespoons of butter over medium heat. As the butter begins to bubble, whisk in ¼ cup of all-purpose flour, stirring constantly for 2-3 minutes until the mixture is lightly golden and foamy.

Gradually pour in 2 cups of whole milk and 1 cup of heavy cream while continuously whisking to prevent lumps. Cook over medium-low heat for about 5-7 minutes until it thickens.

Reduce the heat to low and start adding 2 cups of shredded cheddar cheese and 1 cup of shredded Monterey Jack cheese to the thickened sauce. Stir continuously for about 3-5 minutes, or until all the cheese has melted.

Gently fold in the cooked macaroni using a spatula or wooden spoon, ensuring every piece of pasta is thoroughly coated with the sauce. Season with salt and pepper to taste.

You can serve immediately or preheat your oven to 375°F, transfer to a baking dish, sprinkle with additional cheese and breadcrumbs, then bake for about 20 minutes until golden and bubbly on top.