This creamy low-carb Buffalo chicken and cauliflower casserole is spicy and satisfying. Cauliflower and celery add a tender-crisp bite while a sprinkle of blue cheese on top adds a savory finish.
Preheat oven to 425°F. Line a large rimmed baking sheet with parchment paper.
Place cauliflower on the prepared baking sheet and drizzle with 1 tablespoon oil; toss to coat well and spread in an even layer. Roast until tender, about 15 minutes. Remove from oven. Reduce oven temperature to 375°F.
While the cauliflower roasts, heat the remaining 1 tablespoon oil in a large, deep skillet over medium-high heat. Add onion and celery; cook, stirring often, until the vegetables soften, about 5 minutes. Stir in 1/2 cup scallions; cook, stirring often, until softened, about 1 minute. Add milk and cream cheese; cook, stirring constantly, until the mixture is thickened and smooth, about 1 minute. Remove from heat.
Add the roasted cauliflower, chicken, hot sauce, paprika, garlic powder and the remaining 1/2 cup scallions to the skillet; stir until well combined. Coat a 7-by-11-inch baking dish with cooking spray. Spoon the cauliflower mixture into the baking dish. Sprinkle evenly with blue cheese. Bake until the mixture is bubbly and the blue cheese has melted, about 15 minutes. Garnish with additional scallions, if desired.