Macaroni and Cheese with Cauliflower

Serves 6 | Hands-On Time: 15m | Total Time: 40m
Ingredients

    12 ounces multigrain elbow macaroni
    1 head cauliflower, roughly chopped
    4 slices multigrain bread, torn
    1/2 cup fresh flat-leaf parsley, chopped
    3 tablespoons olive oil
    kosher salt and black pepper
    1 onion, finely chopped
    1 1/2 cups grated extra-sharp Cheddar (6 ounces)
    1 1/2 cups reduced-fat sour cream
    1/2 cup 1 percent milk
    1 tablespoon Dijon mustard