Classic Crispy Top Macaroni and Cheese

Preheat oven to 350℉. First, make the topping by tossing the panko with the melted butter in a medium bowl. Then mix in the cheese. Set aside. Cook the pasta according to the package directions, drain and cover. While the pasta is cooking, melt the butter in a large saucepan and blend in the flour, salt and pepper. Cook until the mixture is bubbly, and then gradually add the milk, stirring while adding. Stir in the Dijon. Over medium heat, cook and stir until the sauce boils, and then simmer for one minute, stirring constantly. Reduce the heat to low, add the cheese, and stir until just melted. Add the pasta to the cheese mixture and toss lightly to coat. Pour into a 9-inch square baking dish (see note), and then sprinkle with the topping. Bake for 20-25 minutes or until the cheese is bubbly and the topping is lightly golden.