Preheat your oven to 425°F, grease one 13x18" baking sheet with one tablespoon of olive oil, and set aside a second 13x18" baking sheet.
Place two tortillas on the long sides of the greased baking sheet, using a total of four tortillas. The tortillas will overlap where they meet in the center, and half the tortilla should hang over the edge of the baking sheet.
Place a tortilla in the middle of the short sides of the baking sheet, using a total of two tortillas. Half of the tortilla should hang over the edge of the baking sheet.
Place a single tortilla in the center of the baking sheet, covering the remaining open space in the center of the pan.
Heat one tablespoon of olive oil in a large frying pan over medium heat. Add the sliced peppers and onions to the pan and cook until soft, about 5-7 minutes.
Remove the cooked peppers and onions from the pan and set them aside. Add the ground turkey to the frying pan and cook the turkey until no pink remains, about 5 minutes.
Return the peppers and onions to the pan with the ground turkey. Add the black beans and mix until well combined.
Sprinkle the fajita seasoning over the ground turkey mixture. Mix until the turkey, peppers, onions, and beans are fully coated in the seasoning, then remove the quesadilla filling from the heat.
Cover the prepared tortilla shells in a layer of shredded cheese.
Top the cheese with the ground turkey and pepper mixture.
Place the remaining tortilla shell in the center of the ground turkey mixture, on top of the filling ingredients.
Fold the overhanging tortilla shells towards the center of the sheet pan, overlapping them as you go. Start with the tortillas on the short sides of the pan and finish with the tortillas on the long sides.
Lightly brush the remaining tablespoon of olive oil on the tops of the tortilla shells, then place the second sheet pan on top of the quesadilla to weigh it down.
Transfer both baking sheets to the oven and bake the ground turkey quesadilla for 20 minutes, then remove the top baking sheet and continue baking the quesadilla for an additional 5 minutes. When finished, remove from the oven and let it cool for at least 10 minutes before slicing into squares.
Top with your favorite quesadilla toppings, serve, and enjoy!