Heat the oven: 425°F. Line a large sheet pan with parchment for easy cleanup.
Add the sweet potatoes to the pan, season with salt and pepper, drizzle with 1 tbsp olive oil. Bake for 10 minutes while you follow the next steps.
Prep the chicken: Pat dry. (Optional) Toss with 2 tbsp cornstarch for extra crisp edges. Add remaining 1½ tbsp oil and remaining spices; season with salt & pepper.
Take the potatoes out of the oven, move to one side.
Season the veg: On the pan, toss cauliflower and peppers with 1½ tbsp oil, half the garlic/onion/paprika, salt & pepper .
Bake: Arrange chicken over the veggies (don’t crowd). Roast 18–22 minutes, stirring once at 12 minutes, until chicken hits 165°F and edges are browned.
Buffalo glaze: In a small bowl, whisk buffalo sauce with melted butter (and honey, if using).
Sauce & finish: Drizzle half the buffalo glaze over the hot pan and toss to coat. (If using cheese, sprinkle now and return to oven 2–3 minutes to melt.)
Ranch drizzle: Stir yogurt + ranch seasoning; thin to drizzleable.
Serve: Top with green onions. Plate with extra buffalo sauce and ranch on the side.