Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish and set aside.

Cook the pasta according to package instructions until al dente. Drain and set aside.

In a large skillet, cook the chopped bacon over medium heat until crispy. Remove with a slotted spoon and place on a paper towel-lined plate. Reserve 1 tablespoon of bacon grease in the pan.

In the same skillet, add the sliced leeks and sauté until soft and slightly caramelized, about 3-4 minutes. Remove from heat and set aside.

In a large saucepan, melt butter over medium heat. Whisk in the flour and cook for 1-2 minutes until lightly golden.

Slowly whisk in the milk and heavy cream, stirring constantly until the mixture thickens, about 3-5 minutes.

Add the Dijon mustard, garlic powder, smoked paprika, salt, and black pepper, and whisk to combine.

Reduce heat to low and stir in cheddar, Gruyère, and Parmesan cheese until melted and smooth.

Stir in the cooked pasta, bacon, and leeks until evenly coated with the cheese sauce.

Transfer the mixture to the prepared baking dish and spread evenly.

In a small bowl, mix panko breadcrumbs, melted butter, and paprika. Sprinkle evenly over the mac and cheese.

Bake for 20 minutes or until the topping is golden brown and crispy.

Remove from oven, garnish with chopped parsley, and serve warm.