Prep and preheat: Heat your oven to 375°F (190°C).
Spray a 9x13-inch baking dish with nonstick spray.
Cook the pasta: Boil in salted water until just shy of al dente. Do not overcook; it will finish in the oven. Drain and set aside.
Crisp the bacon: Cook bacon in a skillet until golden. Drain on paper towels, then crumble.
Reserve about 1 tablespoon of bacon fat if you like extra flavor.
Sauté the veggies: In the same skillet, add olive oil (or bacon fat). Cook the onion and bell pepper over medium heat until soft, 4–5 minutes. Stir in garlic for 30 seconds.
Season with a pinch of salt and pepper.
Make the creamy BBQ base: In a large bowl, whisk together BBQ sauce, cream cheese, and sour cream until smooth. Add smoked paprika and a few grinds of black pepper. Taste and adjust seasoning.
Mix the filling: Add cooked pasta, shredded chicken, sautéed veggies, and half the crumbled bacon to the bowl.
Stir gently to coat everything in the sauce.
Add the cheese: Fold in 1 1/2 cups cheddar and 1/2 cup mozzarella. The rest will go on top.
Assemble: Transfer the mixture to the baking dish. Sprinkle remaining cheddar and mozzarella evenly over the top.
Finish with the remaining bacon.
Bake: Bake uncovered for 18–22 minutes, until the cheese is melted and bubbly and the edges are lightly browned.
Finish and serve: Let it rest for 5 minutes so it sets. Garnish with chopped parsley or green onions. Serve with a simple salad or steamed veggies.