In a medium bowl, mash half of the rinsed and drained black beans until they form a thick paste. Combine the mashed beans with the remaining whole black beans, Greek yogurt, cumin, chili powder, garlic powder, diced red onion, and chopped cilantro. Season generously with sea salt and black pepper, mixing thoroughly.

Lay out the tortillas flat on a clean surface. Spread a portion of the bean mixture over one half of each tortilla, leaving a border for folding. Sprinkle a layer of cheese over the mixture. Fold tortillas in half.

Heat a non-stick skillet over medium heat and add olive oil. Once heated, add two folded quesadillas to the skillet. Cook for about 3-4 minutes until golden brown.

Flip each quesadilla and cook for another 3-4 minutes until crispy and deep golden. Transfer cooked quesadillas to a cutting board.

Slice each quesadilla into wedges and serve warm with salsa, Greek yogurt, or guacamole.