Heat 1 teaspoon of olive oil in a pan over medium heat and add the onion. Cook until they just begin to brown. Add the black beans and sauté just long enough that the black beans are warm. Put mixture aside in a bowl. Combine the butternut squash, cilantro, lime juice, salt, and cayenne pepper in a bowl. Layer 1/4 of the bean and onion mixture on half a tortilla, cover with 1/4 of the butternut squash mixture and 1/4 cup cheese.
Add 1 teaspoon of olive oil to a pan (feel free to use the same one that you cooked the onion in) and set heat to medium-high. Fold over the tortilla and add to the pan. Cook it for about 2 to 3 minutes per side, until the tortilla is browned and the cheese has begun to melt.