Heat olive oil in a skillet over medium heat.
Add onion and bell pepper, sauté until softened, about 3-4 minutes.
Stir in garlic and cook for 30 seconds.
Add ground chicken, cook until no longer pink, breaking it apart with a spatula.
Stir in tomato sauce, ketchup, Cajun seasoning, and smoked paprika.
Season with salt and pepper, reduce heat, and simmer for 5-7 minutes.
Serve the mixture on toasted hamburger buns with optional toppings.