01 - Heat a large skillet over medium heat. Add sliced Cajun-style beef sausage and cook for 3 to 4 minutes, stirring occasionally, until the sausage is golden and slightly crisped. Transfer sausage to a plate and set aside.
02 - In the same skillet, add diced red and green bell peppers along with sliced red onion. Sauté for 5 minutes, stirring until vegetables are softened. Add Cajun seasoning, smoked paprika, salt, and black pepper; stir to combine aromatics and vegetables.
03 - Return cooked sausage to the skillet with the sautéed vegetables. Cook for 2 minutes, stirring occasionally, to blend flavors. Transfer filling to a bowl. Wipe out the skillet to prepare for assembling quesadillas.
04 - Melt 1/2 tablespoon unsalted butter in the cleaned skillet over medium heat. Lay one flour tortilla flat in the skillet. Evenly sprinkle 1/2 cup Monterey Jack cheese and 1/4 cup cheddar cheese over half of the tortilla. Spoon a quarter of the sausage and vegetable mixture over the cheese. Fold the tortilla over to cover the filling.
05 - Cook the filled tortilla for 2 to 3 minutes per side, pressing gently with a spatula, until the exterior is crisp and deep golden brown and cheese is thoroughly melted. Repeat the process with remaining tortillas, butter, cheese, and filling.
06 - Transfer cooked quesadillas to a cutting board. Slice each into wedges using a sharp knife and serve immediately while hot.