Step 1

Preheat oven to 425 degrees F.

Step 2

Place bacon in a large nonstick skillet over medium heat; cook until crisp, 6 to 8 minutes. Transfer to a paper-towel-lined plate and let cool. (Reserve the drippings in the pan.)

Step 3

Combine cauliflower, pepper, salt and the bacon drippings in a 9-by-13-inch baking dish. Roast, stirring twice, until tender, about 35 minutes.

Step 4

Meanwhile, combine 1 cup cheese, sour cream and half the scallions in a small bowl. When the cauliflower is tender, stir the cheese mixture into the cauliflower in the pan. Sprinkle with the remaining 1/4 cup cheese. Bake until hot, 5 to 7 minutes more.

Step 5

Chop the cooled bacon. Sprinkle the hot casserole with thebacon and the remaining scallions.