Bring a large pot of salted water to a boil and preheat the oven to 350 degrees F.Boil the cavatappi until al dente, according to the package directions.
Combine the shredded cheddar and gouda in a large bowl until well mixed. Separate out a quarter of the cheese blend and set aside - you’ll use this to top the mac and cheese later. Use the remaining cheese to make the cheese sauce.
Next, make the cheese sauce. In a small saucepan, melt the butter over medium-low to low heat. Once melted, sprinkle in the flour and stir constantly in a figure-8 motion until the roux puffs up and turns golden, about 3 to 4 minutes.Then, stir in the milk a little at a time, making sure to stir constantly until the milk has been fully incorporated.Finally, stir in the cheese in batches until it's fully melted. Keep an eye on the heat, lowering it if the cheese sauce is steaming too much - you want to keep it as low as possible. Make sure to stir constantly as you add the cheese.Add salt to taste, then remove from heat.
Combine the cheese sauce and cavatappi until the pasta is well coated. Pour the mac and cheese into a 10-inch cast iron skillet, then top evenly with the remaining shredded cheese.
Bake until golden brown and lightly crisped on top, about 15 to 20 minutes.
Garnish with fresh chives, then serve family style.
Notes
Ingredients: Make sure to use high quality cheese for the best taste! Buy the cheese in blocks and shred it yourself for the best melty, gooey texture. As for the noodles, we like using cavatappi for its curly shape - the sauce clings well to these noodles. But you can use shells, macaroni, or any of your other favorite shapes for mac and cheese.Making a roux based sauce: The cheese sauce is made with a roux (a mixture of butter and flour) to make it thick and creamy. The key to a successful roux is to keep the heat low - you don’t want to burn the flour - and to stir constantly. Make sure to cook the roux for a full 3 to 4 minutes. It’s tempting to call it early, but you need to give it enough time to cook the flour - otherwise, the flavor or texture of your cheese sauce might not turn out how it should.Serving suggestions: We like to serve skillet mac and cheese family style by bringing it to the table with a big spoon and digging in! Mac and cheese is quite heavy, so you don’t really need a side to go with it. But if you want to lighten up your meal and add some veggies, we recommend serving this dish with some dressed greens or a side of steamed broccoli.Storing and reheating: You can store mac and cheese in an airtight container in the fridge for up to 4 days. Reheat single servings in the microwave for about 1 to 2 minutes, stirring halfway through.Scaling: This recipe is made for a 10 inch skillet, which is enough mac and cheese for about 2 to 3 people. If you want to double the recipe, you can either use two 10 inch skillets, or try making it in a larger baking dish like a 9x13 glass pan. You won’t get the same crisp on the outside as you do from the hot cast iron, but it’ll still be a delicious baked mac and cheese!