Cook the macaroni in a large pot according to the package directions. While the macaroni cooks, fry the bacon.
When the macaroni is cooked, drain and return to pot. Cover pot and turn off stove.
Melt the butter in a skillet or large saucepan over medium-low heat; stir in flour.
Pour milk into skillet, whisking constantly, until well combined with butter mixture. Add mustard, salt, paprika, and pepper.
Let milk mixture simmer until it begins to thicken slightly. Stir in gouda cheese and all but 1/3 cup of cheddar.
When cheese is melted, stir cheese sauce into macaroni. Serve with crumbled bacon and the remaining cheddar cheese sprinkled on top.