Directions

1. In a large skillet over medium heat, cook the bacon, stirring occasionally, until crisp, 15 to 18 minutes. Use a slotted spoon to transfer the bacon to a paper towel-lined plate. Set aside.
2. While the bacon is cooking, in a large saucepan or small stockpot, cook the pasta according to package directions. Drain and set aside.
3. Wipe out the saucepan or small stockpot and return it to medium heat. Add the butter. When the butter is melted, sprinkle in the flour, salt, and pepper and cook, whisking, for 2 minutes. Slowly add the milk, whisking. Continue cooking and whisking until the mixture thickens, about 3 minutes. Reduce the heat to low and stir in the cheeses. Stir in the pasta and pesto. Set aside 1 cup of bacon and stir in the remaining bacon. Add more salt and pepper to taste.
4. Serve immediately, garnished with the reserved bacon. (If mixture gets too thick as it cools, stir in additional milk.)