Pre-heat oven to 200°F.
Heat the olive oil in a large skillet over medium heat.
Lightly salt and pepper the chicken pieces.
Cook the chicken in the oil until no longer pink, about 8 minutes.
Add the taco seasoning and flour and stir to coat the chicken pieces.
Add the chicken stock and simmer for about 8 minutes, or until slightly thickened.
Using a slotted spoon, remove the chicken from the skillet to a medium bowl, and pour the sauce into another bowl. Set both aside.
In a non-stick skillet, heat 1 teaspoon of the vegetable oil and when hot, add 1 tortilla.
To the tortilla add a handful of cheese, then a pinch of scallions, then about 1/2 cup cooked chicken.
Moving quickly, spoon over a couple spoonfuls of the cooked sauce and green enchilada sauce (if using).
Using a garlic press, press one garlic clove over the top, or if not using a garlic press, sprinkle about 1/4 teaspoon of the minced garlic over the top.
Top with another handful of cheese and top with another tortilla.
Using a spatula and carefully holding the top tortilla, flip the quesadilla.
Cook until nicely browned on both sides. Remove from skillet and place on a baking sheet and place in oven to keep warm.
Repeat the process for remaining 3 quesadillas.
Cut into fourths and serve with salsa and sour cream.