Make the sauce. Stir yogurt and barbeque sauce together in a small bowl until thoroughly mixed. Cover and refrigerate until serving time.
Cook the sweet potato. Place diced potato into a microwave safe bowl with a spoonful of water. Cover and cook on high for 3-5 minutes or until potato is tender. Set aside.
Heat a large non-stick skillet and add the olive oil. Saute the sliced shallot for a minute and then add the kale. Season to taste with salt and pepper. Saute the kale for a couple of minutes, stirring to keep everything from sticking.
Add 2 Tablespoons of water to the pan and cover until the kale is wilted and cooked to desired tenderness. When water evaporates, if kale isn't done, add another couple of tablespoons of water and continue to cook. If your water evaporates before your kale is finished cooking, add another couple of tablespoons of water and continue to cook, covering to keep the steam in the pan. Mine took about 10 minutes and I used about 6 Tablespoons of water.
Add the black beans and corn and cover until the mixture is heated through. If you have any residual liquid in the pan, remove the cover and let it cook off. You want your mixture moist but not dripping with liquid. Taste and add more salt/pepper, if necessary.
Build the quesadillas. Lay four tortillas on your work surface. Take a spoonful of cheese and sprinkle evenly over each tortilla. Add 1/4 of the kale mixture, then top with 1/4 of the sweet potatoes. Sprinkle cheese on the top, then top each with another tortilla.
Preheat a griddle or clean frying pan to medium heat. I cook these at 350-375 degrees F. on my griddle. Spray lightly with cooking spray. Carefully place tortilla on griddle/pan. Press down during cooking. This will help the tortilla hold together. When the cheese melts and the bottom is browning, carefully flip to cook on the other side. This will take about 2 minutes or so per side.
Remove to a cutting board and cut into wedges. Serve with creamy barbeque dip.