Heat 1 tablespoon olive oil in a skillet over high heat. Marinade diced chicken with salt, pepper, and taco seasoning. Add the chicken to the skillet and sauté over medium-heat until done, about 5 minutes on each side. Remove from skillet and set aside.
Add 1 tablespoon olive oil to the skillet and add in sliced onions and peppers and cook for 2-3 minutes. Add 1 cup of corn and cook for an additional 3-4 minutes. Add salt and pepper to taste.
In a separate griddle, sizzle 1 teaspoon butter and lay a flour tortilla. Build the quesadilla by layering shaved manchego cheese, and then arranging the chicken and cooked onions, peppers, and corn. Add jalapeno peppers and sliced avocado (if desired). Top with the second tortilla.
When the tortilla is golden on the first side, carefully flip the quesadilla to the other side. Continue cooking until the second side is also golden. Slice and serve.