1. In a medium-sized pan add the chicken breast fillets. Add 1 cup water and boil the chicken, flipping occasionally until cooked through.
2. Transfer the chicken to a bowl and shred using two forks. Add the taco seasoning and taco sauce. Mix and adjust salt and spice accordingly. Set aside and prepare the other ingredients.
3. Heat a cast-iron pan on a medium-low flame. Melt a little butter in the pan then place one tortilla in the pan.
4. Spread 1/4 cup cheese on one half of the tortilla. Add 2 tablespoons of shredded chicken to the half as well as some black beans and chopped bell peppers.
5. Add 1 tablespoon of cheese on top of the filling, then fold the tortilla over the toppings and press down.
6. Flip the quesadilla carefully once the bottom is golden brown and cook on the other side till the tortilla is crispy and golden brown as well.
7. Serve with a dollop of sour cream and some salsa on the side.
8. Repeat the same process for as many quesadillas as you want to make.

You will have some chicken leftover. Store it in an airtight container in the fridge for up to 3 days.