Skillet Mac & Cheese with Summer Squash and Pimiento

Ingredients:

1. Preheat oven to 400°F. Bring a large saucepan of water to a boil.
2. Cook macaroni 1 minute less than the package directions for al dente. Drain and set aside.
3. Meanwhile, heat 1 Tablespoon oil in a large ovenproof skillet over medium-high heat. Add onion and cook, stirring, until starting to brown, about 2 minutes. Add zucchini (and/or summer squash) and 1/4 teaspoon each salt and pepper; cook, stirring, until starting to soften, 2 to 3 minutes. Transfer to a bowl.
4. Reduce heat to medium and melt butter in the skillet. Sprinkle with flour and whisk until fragrant, 1 to 2 minutes. Whisk milk, dry mustard, cayenne and the remaining 1/4 teaspoon each salt and pepper in a small bowl. Slowly pour the milk mixture into the skillet, whisking constantly. Cook, stirring, until the sauce is thick enough to coat the back of a spoon, 3 to 5 minutes.
5. Remove from heat and stir in cheese and pimientos. Using a slotted spoon, add the reserved vegetables to the skillet along with the pasta. Stir to coat.
6. Mix panko, garlic powder and the remaining 1 Tablespoon oil in a small bowl. Sprinkle over the casserole. Transfer to the oven and bake until the sauce bubbles and top is golden, about 15 minutes.