Assemble quesadillas by sprinkling cheese, caramelized onions, butternut squash, and black beans on half of each tortilla, then fold over.
Heat oil in a skillet over medium-low heat. Cook each quesadilla until browned, flip, then cook until cheese melts. Repeat with remaining quesadillas, adding oil as needed.
Mix sour cream, heavy cream, and hot sauce to make the crema.
Cut quesadillas into quarters, drizzle with crema, and serve topped with avocado, cilantro, and salsa verde.
Notes
For extra flavor, toast the tortillas lightly before assembling.