Preheat the oven to 375°F (190°C). Lightly grease a 9 × 13-inch baking dish. Spread ½ cup (120 mL) of the red enchilada sauce evenly over the bottom of the dish. Reserve another ½ cup (120 mL) of sauce for the filling and the remaining 1 cup (240 mL) for covering the enchiladas.

Heat the olive oil in a large skillet over medium heat. Add the diced onion and red bell pepper. Cook for 4–5 minutes, stirring occasionally, until the vegetables begin to soften. Add the minced garlic and cook for another 30 seconds, until fragrant. The vegetables should be tender but still retain a little texture.

Reduce the heat to medium-low: Add the cooked shredded chicken, drained black beans, green chiles, cumin, smoked paprika, kosher salt, and black pepper to the skillet. Pour in the reserved ½ cup (120 mL) of enchilada sauce. Stir gently for 1–2 minutes, until the chicken and beans are evenly coated and warmed through. The filling should be moist enough to hold together without having excess liquid pooling in the skillet.

Remove the skillet from the heat and allow the filling to cool for a couple of minutes. Stir in the shredded Monterey Jack cheese until it is evenly distributed. The residual heat will soften the cheese slightly, helping bind the chicken and vegetables together.

Warm the flour tortillas briefly in a dry skillet over medium-low heat or in the microwave under a slightly damp paper towel. The tortillas should be soft and flexible enough to roll without tearing. Avoid overheating them, as dry or stiff tortillas are more likely to split during assembly.

Place a tortilla on a clean work surface: Spoon approximately one-eighth of the chicken filling along the center. Fold the sides slightly inward if desired, then roll the tortilla around the filling. Place it seam-side down in the prepared baking dish. Repeat with the remaining tortillas and filling, arranging the eight enchiladas snugly in the dish.

Pour the remaining 1 cup (240 mL) of red enchilada sauce over the assembled enchiladas. Spread the sauce evenly with the back of a spoon, making sure the exposed tortilla edges are lightly coated. Cover the baking dish tightly with aluminum foil.

Place the covered baking dish on the center oven rack. Bake for approximately 20 minutes, until the sauce is bubbling gently around the edges and the filling is heated through. Carefully remove the foil, keeping your hands away from the escaping steam.

Sprinkle the orange cheddar evenly over the enchiladas: Return the dish to the oven, uncovered, and bake for another 10–15 minutes, until the cheese is completely melted and the edges are lightly golden. The center of the enchiladas should reach 165°F (74°C) before serving.

While the enchiladas finish baking, cut the optional black olives into small triangles, narrow strips, or curved pieces. For jack-o'-lantern-inspired decorations, use triangle-shaped pieces for eyes and noses and small strips to suggest smiling mouths. Keep the decorations simple so they are easy to arrange on the melted cheese.

Remove the enchiladas from the oven and let them rest for 5 minutes. While the cheese is still warm, arrange the optional black olive pieces on top to create small jack-o'-lantern faces or other Halloween designs. Let the dish rest for another 5 minutes before serving. This gives the filling time to settle and makes the enchiladas easier to lift from the baking dish.

Sprinkle the optional chopped cilantro around the decorated enchiladas, avoiding the olive designs if you want them to remain clearly visible. Serve with optional sour cream and lime wedges on the side. Use a wide spatula to transfer each enchilada to a plate, keeping the filling and melted cheese intact.