In a small bowl mix together all ingredients for quesadilla sauce until well combined. Cover and refrigerate at least 1 hour for flavors to blend.

Heat olive oil in a skillet over medium heat. Add chicken and taco seasoning. Stir to coat and cook until chicken is cooked all the way through. Set aside. SHORTCUT: Use precooked chicken. Cube just under 1/2" and just heat in skillet with seasoning until warmed through. This is one way I use up leftover rotisserie chicken!

Heat a 12" skillet over medium low heat (I moved my chicken to a bowl, and rinsed out and dried the skillet I used for it). When skillet is heated, brush one side of one flour tortilla with about a teaspoon of melted better. Place buttered side down in skillet.

On one half of tortilla, sprinkle 1/4 cup of EACH shredded cheese, 1 slice American cheese torn into pieces and 1/2 cup of chicken in even layers. On opposite half of tortilla, the "empty" side, spread 1-2 tbs of quesadilla sauce (depending on how saucy you want it, I used 2tbs lol).

Allow to cook opened until cheese begins to melt around the edges. Fold sauce half of tortilla on top of filling half. Gently press down on quesadilla with back of a spatula to squish everything together. Continue cooking on first side until cheese is melted, about 2 minutes. Carefully flip, press and cook 2 minutes more for a lightly golden finish on both sides (Longer for a darker finish if you want).

Repeat with remaining ingredients for 4 quesadillas. As each is finished, transfer from skillet to a plate to rest a few minutes before cutting. Cut each quesadilla into 4 pieces (I used my pizza cutter), serve and enjoy!