13.25-oz box of whole wheat elbow macaroni
2 Tbsp olive oil
1 leek, trimmed, washed, and chopped
12 oz sliced mushrooms (I love cremini or baby bella)
3 Tbsp chopped fresh thyme
4 Tbsp butter
1/2 cup all-purpose unbleached flour
4 cups skim (nonfat) milk
8 oz gruyere or Danish fontina cheese, grated
1 tsp kosher salt
1-1/2 tsp black pepper
3/4 cup panko bread crumbs
2 Tbsp chopped flat-leaf parsley
1/4 cup Parmigiano-Reggiano cheese
Olive-oil cooking spray
Preheat oven to 375°F. Lightly coat a straight-sided casserole dish (approx. 9x11 inches) with cooking spray.
Bring a large pot with 6 quarts of water to a boil. Add macaroni; cook until al dente according to package instructions, about 8 minutes. Drain, and transfer to a large bowl.
In a large nonstick frying pan, heat the oil over low heat, and sauté the chopped leek for 2 minutes, until quite soft. Add the mushrooms and thyme, stir to combine, and cook for 4-5 minutes, until the mushrooms have given off their liquid and are lightly browned. Set aside to cool slightly.
In a small sauce pan, heat the butter over medium heat, and when it bubbles, sprinkle in the flour. Stir vigorously so the butter absorbs the flour, about 1 minute. Then, slowly pour in the milk, whisking steadily to make sure there are no lumps. Let the milk cook, stirring frequently, for 5 minutes or until the sauce thickens enough to coat the back of a wooden spoon. Remove the pot from heat, and stir in the gruyere, salt and pepper.
Pour the cheese sauce into the macaroni, and add the cooled mushroom mixture. Stir to combine.
Transfer noodle mixture to the prepared dish. In a small bowl, combine panko, remaining parmesan cheese, and parsley. Sprinkle evenly over noodle mixture.
Place in the oven, uncovered, and bake for 25-30 minutes, until the top is browned and the cheese is bubbling a bit along the edges. Remove from the oven, let sit for 5 minutes, and serve hot.
Serve immediately, or let cool and refrigerate for up to two days. As fantastic as this is on the first day, it's even better on the second day.