Preheat your oven to 325°F (165°C) and grease a 3-quart baking dish.

Boil water, add salt, and cook elbow macaroni 1-2 minutes less than package instructions. Drain and set aside.

Combine shredded cheddar cheese and Gruyère cheese in a medium bowl; set aside.

Melt butter in an empty pot over medium heat, add flour to form a roux, whisk until light golden brown.

Gradually stir in half the milk, then add remaining milk and heavy cream; cook until thickens (5-7 mins).

Remove from heat and stir in half of the cheese mixture until melted and creamy.

Fold cooked macaroni into the cheese sauce until completely coated.

Layer half of the macaroni mixture in the baking dish, sprinkle some cheese, then add the rest of the macaroni and cheese mixture.

Bake in preheated oven for 13-15 minutes until bubbly and golden, then broil for 2-3 minutes for a crispy layer.

Let rest for a few minutes before serving.