Bring a large saucepan of salted water to a boil and cook pasta according to package directions.
While the pasta is cooking, melt the butter in a large saucepan over medium heat. Add the flour and cook, whisking constantly until golden, about 2 minutes. Continue whisking and add the milk in a slow, steady stream. Bring the mixture to a steady simmer, whisking constantly, and whisk until thickened, about 2 minutes.
Drain the pasta in a colander. Remove the sauce from the heat, add the cheese, and stir until the cheese melts. Immediately add the hot, drained pasta and stir until well-coated. Stir in Worcestershire sauce, salt, pepper and nutmeg.
Divide the mac and cheese among four 6-ounce ovenproof ramekins and sprinkle 1 tablespoon bread crumbs over each. Broil until crumbs are golden and crisp, 1 to 2 minutes, taking care not to let the top burn. Serve immediately.