Step 1

Preheat oven to 375 degrees F and lightly grease a 2-quart ovensafe casserole dish. Set aside.

Step 2

Bring a large pot of water to a boil and cook the pasta until al dente, following the directions on the pasta package. You’ll want it to still have a bite to it because it will finish cooking in the oven.

Step 3

In the meantime, in a large skillet, melt butter over medium-high heat. Whisk in the flour and cook for 1 to 2 minutes while whisking vigorously so it doesn’t burn. Continue to whisk as you add the milk, then let the mixture gently come to a simmer and thicken, about 5 minutes.

Step 4

Add the Gruyere and white cheddar cheeses to the skillet and stir together with a spatula until all the cheese has melted. Add salt and pepper, to taste. Remove the skillet from the heat.

Step 5

At this point, the pasta should be done cooking. Drain well and add to the cheese sauce. Gently toss the pasta with the cheese sauce until everything is covered. Sprinkle half the bacon mixture into the skillet and toss to incorporate.

Step 6

Pour pasta mixture into prepared casserole dish. Top with remaining bacon pieces, and then place, uncovered, in oven to bake for 30 minutes, or until mixture is bubbly and pasta is cooked through.

Step 7

After 30 minutes, remove from oven and let sit for 10 minutes before serving.