Preheat and prep. Heat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.

Cook the base. Boil the pasta in salted water until just shy of al dente (about 1 minute less than package). Drain well. If using potatoes, boil until fork-tender. Set aside.

Sauté the veggies. In a skillet, warm a drizzle of olive oil over medium heat. Cook the onion and bell pepper with a pinch of salt for 3–4 minutes until slightly soft. Stir in corn and cook 1 more minute. Remove from heat.

Make the sauce. In a large bowl, whisk together BBQ sauce, sour cream, and chicken broth. Add garlic powder, smoked paprika, and a few grinds of black pepper. Taste and adjust salt if needed.

Combine the filling. Add cooked chicken, pasta (or potatoes), and the sautéed veggies to the bowl. Fold in 1 cup of shredded cheese. Mix until everything is evenly coated.

Assemble the casserole. Spread the mixture into the baking dish. Top with the remaining 1 cup of cheese. If using, toss crushed chips or crackers with melted butter and sprinkle over the top for crunch.

Bake. Bake uncovered for 20–25 minutes, until the cheese is melted and bubbling around the edges. If you like a deeper golden top, broil for 1–2 minutes at the end, watching closely.

Rest and garnish. Let the casserole rest for 5–10 minutes so it sets. Garnish with green onions or parsley. Serve warm.