Swanky Stovetop Mac and Cheese

1/2 pound dry pasta (elbow macaroni, ziti, rotini, etc.)
1/2 cup chopped yellow onion
2 tablespoons butter
2 tablespoons flour
2 cup whole milk (OR 1 cup skim milk and 1 cup half-and-half)
1 1/2 cup grated or cubed Havarti with dill
1 1/2 cup grated or cubed Gruyere cheese

Optional: bread crumbs, tomato slices

Boil pasta according to directions, draining when finished. In large saucepan, melt butter, stirring in flour till bubbling and starting to brown slightly. Add milk, continuing to stir. As the béchamel sauce thickens, add cheese, still stirring until melted. Mix in pasta and serve, topping with either bread crumbs or tomato slices if desired.

The basic cheese rule applies, soft melty cheeses can be substituted for each other and stronger, more flavorful cheeses can sub for each other as well. This recipe is best with one of each.