Adapted from this Eating Well recipe. Here's my version:
8 ounces whole-wheat penne
1 small head of broccoli cut up into pieces
1/2 head cauliflower cut into pieces
1 tablespoon extra-virgin olive oil
1/2 cup finely chopped onion
1/2 cup cider vinegar
3 cups low-fat milk
3 tablespoons all-purpose flour
3/4 teaspoon salt
1/2 teaspoon freshly ground pepper
1 cup Swiss cheese
2 boneless, skinless chicken breast cooked
1. Bring a large pot of water to a boil. Add pasta and cook for 5 minutes. Add cauliflower and broccoli florets and cook until the pasta and vegetables are tender, about 4 minutes more. Drain, rinse and return to the pot.
2. Meanwhile, heat oil in a large saucepan over medium heat. Add onion and cook, stirring, until tender, 2 to 3 minutes. Add vinegar and cook until reduced slightly, about 1 minute.
3. Whisk milk, flour, salt and pepper together in a medium bowl and add to the pan. Bring to a boil over medium-high heat, stirring frequently. Cook, stirring, until thickened, about 1 minute. Reduce heat to low and stir in cheese until smooth.
4. Stir chicken into the cheese sauce; cook until heated through, about 2 minutes. Stir the sauce into the drained pasta and cauliflower.