Sweet Potato, Black Bean and Spinach Quesadilla

Heat broiler. Line a large broiler-proof baking sheet with foil. Place the sweet potatoes on a plate, cut-side down, and microwave on high until tender, 5 to 7 minutes. Heat the oil and garlic in a large skillet over medium heat until the garlic just starts to sizzle. Stir in the cumin, cinnamon, and cayenne, and cook for 30 seconds. Add the beans and 1/2 cup water and cook, tossing occasionally until heated through, about 2 minutes. Add the spinach and cook, tossing until just beginning to wilt, about 1 minute; remove from heat. Place the tortillas on the prepared baking sheet. Scoop the sweet potato from the skins and spread on one half of each tortilla. Top with the bean mixture and cheese, then fold over the tortillas to cover the filling (they will look overstuffed). Broil until the top is golden brown and the cheese has melted, about 2 minutes. Serve with lime wedges and salsa if desired.