Macaroni and Cheese

3 tablespoons butter plus butter for gratin dish
salt to taste
3/4 pound macaroni or other pasta
2 tablespoons minced yellow onion or shallot
3 tablespoons all purpose flour
3 cups milk (at least 1 % milkfat), heated
1 teaspoon paprika plus extra for sprinkling
1/4 teaspoon cayenne pepper
fresh ground black pepper to taste
2 cups grated Cheddar cheese
1 cup bread crumbs

Preheat oven to 375 degrees and lightly butter 2 quart gratin dish
Cook pasta in boiling water with a little salt
While the pasta is cooking, melt the butter in a 2 quart saucepan with the onion over medium heat
Stir in flour and cook, stirring for 2 minutes
Whisk in hot milk, paprika and cayenne
Continue stirring until thick then cook 3 minutes longer
Season to taste with salt and pepper
When pasta is almost done but still somewhat chewy, drain it, the return it to the pan
Stir in sauce and cheese
Turn mixture into prepared dish, cover top with crumbs and add a few dashes paprika
Bake until crust has formed and crumbs are brown, about 30 minutes