To assemble the quesadillas, spread a quarter of the cheeze/spinach mixture onto a tortilla shell — leaving a 1" border around the edge so that the mixture does not leak out during cooking. Note: the mixture will likely appear quite runny, surprisingly however, it does hold together quite well, even after cutting the final quesadilla.
Next, place a quarter of the onions and black beans onto one half of the tortilla shell. Fold the tortilla in half and set aside while you assemble the remaining quesadillas.
Alternatively, the quesadillas can be fully assembled while they are in the frying pan. This just avoids having to transfer them once they are assembled. In this case, it's easier to assemble and cook them one at a time.
To cook the quesadillas, heat a large fry pan over medium high heat. Once hot, carefully transfer two quesadillas to the fry pan. Cook on the first side until golden brown, about 2-3 minutes and then flip and let cook for a minute or two on the other side. Remove and let cool for a minute before cutting. Continue with the remaining quesadillas.
Lastly, cut each quesadilla in half and serve with some of the mango chutney and a dollop of
Cashew Sour Cream. Note, since the quesadilla itself it quite creamy, the sour cream is not really necessary, it just looks nice. The mango chutney however is highly recommended as it pairs extremely well with the rich and creamy quesadilla.