01 - Preheat the oven to 400°F. Lightly grease a 9x13-inch baking dish and set aside.
02 - Heat olive oil in a large skillet over medium heat. Add the diced onion, minced garlic, and diced bell pepper. Cook for 3 to 4 minutes, stirring occasionally, until the vegetables are softened and fragrant.
03 - Add the ground turkey to the skillet along with the ground cumin, paprika, chili powder, dried oregano, salt, and black pepper. Cook for 5 to 6 minutes, breaking the meat apart with a spoon, until fully browned and no longer pink.
04 - Stir the drained black beans and drained diced tomatoes into the turkey mixture. Simmer for 3 minutes to allow the flavors to meld, then remove from heat.
05 - Spread half of the diced sweet potatoes in an even layer across the bottom of the prepared baking dish. Spoon half of the turkey and black bean mixture over the sweet potatoes, spreading it gently to cover.
06 - Repeat the layering with the remaining sweet potatoes, followed by the remaining turkey and black bean mixture, creating an even top surface.
07 - Cover the baking dish tightly with aluminum foil and bake for 25 to 30 minutes, or until the sweet potatoes are nearly tender when pierced with a fork.
08 - Remove the foil and sprinkle the shredded Monterey Jack or cheddar cheese evenly over the top. Return to the oven uncovered and bake for 10 minutes, or until the cheese is fully melted and bubbly.
09 - Remove from the oven and let the bake rest for 5 to 10 minutes to set. Garnish with chopped fresh cilantro and serve with sour cream on the side if desired.