Prepare the Seasoning Mix
In a small bowl, combine salt, chili powder, black pepper, onion powder, garlic powder, and ground cumin.
Cook the Onions and Chicken
Heat 1 tablespoon of vegetable oil in a skillet over medium heat.
Add diced onions and sprinkle with the seasoning mix.
Sauté for 4-5 minutes until soft, then add the chopped chicken and toss to combine. Remove from heat.
Assemble the Quesadillas
Mix the shredded cheeses in a bowl.
If using, brush one side of each tortilla with oil for extra crispiness.
Heat a large skillet or griddle over medium-low heat.
Place a tortilla on the skillet, oiled side down if brushed.
Sprinkle a portion of cheese on one half of the tortilla, add chicken and onion mixture, then top with more cheese.
Fold the tortilla in half.
Cook the Quesadillas
Cook for 2-3 minutes on one side until golden brown, then carefully flip and cook for another 2-3 minutes.
Repeat with remaining tortillas and filling.
Serve and Enjoy
Remove from skillet, let rest for a minute, then cut into triangles.
Serve warm with sour cream, salsa, or guacamole.