Cook the Pasta: Start by boiling a large pot of salted water. Place the elbow macaroni into boiling water and cook until it reaches al dente firmness, as directed on the packaging. Drain the pasta and set it aside.
Preparing the Cheese Sauce: Start by melting the butter in a medium saucepan over medium heat. Add the minced garlic to the pan and sauté until it releases its aroma, about one minute. Stir in the flour and cook, whisking constantly, until the mixture is bubbly and lightly golden, about 2 minutes.
Incorporating the Dairy: Slowly whisk in the milk and heavy cream, making sure to break up any lumps. Keep stirring continuously as the mixture cooks and begins to thicken, which should take about 5 to 7 minutes.
Melt the Cheese: Reduce the heat to low, then add the shredded cheddar and Gruyère cheeses, one handful at a time, whisking until fully melted and smooth. Blend in the Dijon mustard, smoked paprika, and season with salt and pepper according to your preference.
Combine with Pasta: Add the cooked macaroni to the cheese sauce, stirring until the pasta is thoroughly coated.
Prepare the Topping: In a small bowl, combine the panko breadcrumbs with a tablespoon of melted butter. Stir until the breadcrumbs are evenly coated.
Bake: Preheat your oven to 350°F (175°C). Transfer the mac and cheese to a baking dish and spread it out evenly. Sprinkle the breadcrumb mixture over the top. Cook in the oven for 25-30 minutes, or until the top turns a golden brown and achieves a crispy texture.
To Garnish and Serve: After removing from the oven, let the dish cool down slightly. If you like, sprinkle fresh parsley over the top before serving.