Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish.

Bring a large pot of salted water to a boil. Cook the elbow macaroni 1-2 minutes shy of al dente according to package directions. Drain well and set aside.

In a large heavy pot or Dutch oven, melt the butter over medium heat. Sprinkle in the flour and whisk constantly for 2 minutes to cook the flour.

Slowly pour in the warm milk while whisking vigorously to prevent lumps. Continue to cook and whisk over medium heat for 5-7 minutes until the sauce has thickened.

Remove the pot from the heat. Stir in the salt, pepper, garlic powder, and smoked paprika.

Add the grated gruyere and 2 cups of the grated cheddar cheese. Stir gently off the heat until the cheese is completely melted and the sauce is smooth.

Fold the cooked macaroni into the cheese sauce until well coated. Pour the mixture into the prepared baking dish.

Sprinkle the remaining 1 cup of cheddar cheese evenly over the top. Bake uncovered for 25 to 30 minutes, until bubbly and golden brown on top.