Macaroni and Broccoli and Mushrooms and Cheese

4 ounces grated Cheddar
2 ounces finely grated Parmigiano-Reggiano or other hard cheese
1 tablespoon unsalted butter
1 small yellow onion, chopped
6 ounces cremini or white button mushrooms, sliced
3 tablespoons unbleached all-purpose flour
3 cups low-fat or fat-free milk
1 tablespoon Dijon mustard
1 tablespoon minced tarragon leaves or 2 teaspoons dried tarragon
1/2 teaspoon salt
1/2 teaspoon freshly ground black pepper
8 ounces dried whole-wheat pasta shells (not the large ones for stuffing), cooked and drained according to the package instructions
4 cups small broccoli florets, cooked in boiling water for 1 minute (broccoli can be added to the pasta during the last minute of cooking, then drained with the pasta in a colander)

1. Mix the Cheddar and Parmigiano-Reggiano in a medium bowl. Set aside.

2. Melt the butter in a large, high-sided, oven-safe skillet. Add the onion and cook, stirring often, until softened, about 3 minutes.

3. Add the mushrooms and cook until they release their liquid and it comes to a simmer, and then reduces by about two-thirds, about 5 minutes.

4. Sprinkle the flour over the vegetables in the skillet. Stir well to coat.

5. Whisk in the milk in a steady, thin stream until creamy. Then whisk in the mustard, tarragon, salt and pepper. Continue whisking until the mixture starts to bubble and the liquid thickens, about 3 minutes.

6. Remove the skillet from the heat. Stir in three-quarters of the mixed cheeses until smooth. Then stir in the cooked pasta and broccoli.

7. Preheat the broiler after setting the rack 4 to 6 inches from the heat source. Meanwhile, sprinkle the remaining cheese over the ingredients in the skillet. Set the skillet on the rack and broil until light browned and bubbling, about 5 minutes. (If your skillet has a plastic or wooden handle, make sure it sticks outside the oven, out from under the broiler, so the handle doesn’t melt.) Cool for 5 to 10 minutes before dishing up.

Yield: Makes six side-dish servings.