Step 1

Place oven rack on middle rack, preheat oven to 450 degrees F, and generously coat 8×8-inch baking dish in nonstick cooking spray.

Step 2

Microwave frozen cauliflower florets then frozen broccoli florets until tender, according to instructions on bags.

Step 3

While vegetables cook, in a large skillet over medium heat, cook bacon until crispy. Transfer cooked bacon to a paper towel-lined plate, then crumble into pieces.

Step 4

In a small mixing bowl, stir together shredded cheeses. Then, in a separate mixing bowl, mix together sour cream, cream cheese, mayonnaise, and spices. Open bags of steamed vegetables and pour out any extra water. Then, into bowl of cream sauce, fold in veggies, half of the crumbled bacon, and ~1 cup of shredded cheese mixture.

Step 5

Transfer cream sauce mixture to prepared baking dish and, using a rubber spatula, spread into an even layer. Sprinkle remaining shredded cheese mixture, then remaining bacon crumbles on top.

Step 6

Cover dish with foil, transfer to oven, and bake for 12-15 minutes. Then, remove foil, move oven rack to top rack and turn on oven broiler. Broil casserole until cheese on top is bubbly and golden, about an additional 1-2 minutes, watching carefully to ensure it doesn’t burn.

Step 7

Remove dish from oven, allow casserole to cool slightly before garnishing with chopped green onions and serving.