Salt
1 small head or bundle broccoli, trimmed into florets
1 small head cauliflower or half a large head, trimmed and cut into florets
1 cup penne or other short-cut pasta
1/3 cup sour cream or reduced fat sour cream
1 tablespoon Dijon mustard
1/3 cup chives, finely chopped
1 clove garlic, peeled and grated or crushed into paste
A few drops of hot sauce
Freshly ground black pepper
1 cup grated extra-sharp cheddar cheese, divided

Bring a large pot of water to a boil over medium heat. Salt the water and add the broccoli and cauliflower florets. Boil the vegetables for 5 minutes, then remove them with a spider or a strainer and drain. Add the pasta to the water and undercook by about 2 minutes, then drain.

Meanwhile, combine the sour cream in a large bowl along with the mustard, chives, garlic, hot sauce and salt and pepper, to taste. Add the pasta and cauliflower and two-thirds of the cheese. Stir to combine, then transfer to a casserole or baking dish and cover with the remaining cheese. Cool and chill for a make-ahead meal.
To heat and eat, place the casserole on baking sheet and bake it in the middle of a pre-heated 400°F oven until deeply golden and bubbly, about 40-45 minutes.