Step 1

In a large pot of salted water, boil the pasta to al dente. Drain the pasta and set aside to dry.

Step 2

In the same pot over medium heat, melt the butter. Whisk in the flour, a bit at a time, until completely combined, and continue to whisk until golden, about 2 minutes. Slowly whisk in the milk until smooth and continue to whisk until the sauce is thick enough to coat the back of a spoon. Mix in the salt, garlic powder, and cayenne powder.

Step 3

Add in the cheddar, gruyere, and half of the parmesan, a handful at a time, stirring until melted entirely. Toss the cooked pasta in with the sauce mixture and transfer to an oven safe skillet or baking dish. Top with the remaining grated parmesan.

Step 4

Broil until the cheese on top gets bubbly and begins to brown on the edges, about 3-5 minutes. Sprinkle with chopped chives and serve.