Prepare the black bean filling by adding the olive oil to a large skillet over medium-high heat. Saute the onion and bell pepper until they soften, about 8 minutes. Add a splash of water, as needed, to help prevent sticking.

While the veggies are cooking, add the vegan nacho cheese ingredients to a high-speed blender, and blend until totally smooth. You can taste and adjust any flavoring as needed. Set this aside while you finish the filling.

When the onion and peppers are tender, add in the drained black beans, cumin, oregano, chili powder, cayenne pepper, and salt, and stir well. Add in the fresh spinach, and continue stirring and cooking until the spinach has wilted.

Transfer the cooked black bean filling to a large bowl, and rinse and dry the large skillet so you can re-use it. Add a small drizzle of olive oil to the pan, and spread it around so it’s lightly coated. (Don’t use too much!) Add the tortilla to the pan, so it can start heating up.

Spread a thin layer of the cheese sauce over the entire top of the tortilla, then add the black bean filling to only half of the tortilla. Let it cook for 2 to 3 minutes, until the tortilla starts to look golden on the bottom.

Fold the tortilla in half, covering the half with the black bean filling, then use a spatula to transfer the quesadilla to a plate. Cut it into triangles, and serve warm, with salsa and guacamole. Leftover filling and cheese sauce can be stored separately in the fridge for up to 5 days.