Preheat oven to 200 degree Fahrenheit (to keep quesadillas warm while cooking batches).
Heat olive oil in a pan (I used non-stick pan) over medium heat.
Once oil is hot, add ground beef, chili powder, chipotle powder, oregano, cumin, garlic powder, onion powder, salt, pepper and cayenne pepper powder (if using). Heat until cooked through, breaking into crumbles with a wooden spoon, about 8 to 10 minutes or so. Stir in tomato paste and stock/broth and cook 1 to 2 minutes more.
Remove beef from the pan and place into a bowl. If there is any excess grease drain/remove.
Distribute about 8 ounces (or 2 cups) of cheese among all tortillas (on one side of them). Note: Reserve the remaining 4 ounces (or 1 cup of cheese).Also, if your tortillas are smaller or larger than the size I used, the quantity you yield may vary. Distribute ground beef on top of cheese. Then, sprinkle remaining 1 cup (or 4 ounces) of cheese on top of ground beef. Fold over each tortilla so it's a half-moon shape.
To cook quesadillas, grease pan with cooking spray or oil. Heat over medium-low heat. Note: Cook the quesadillas in batches, two quesadillas at a time, adding more cooking spray or oil to the pan between batches. Place two quesadillas in the pan. Cook quesadillas for about 2 minutes on one side.
Carefully flip quesadillas to the other side and continue to cook for another 2 minutes or until they're golden brown and crispy on the outside and the cheese is melted inside (carefully watch to ensure they don't burn). Transfer cooked quesadillas to a baking sheet and place into your preheated oven to keep warm while you are continuing to cook the remaining quesadillas.
Repeat process to cook remaining quesadillas.
Once done, cut each half-moon (quesadilla) in half so you have 12 pieces. Great served with salsa, guacamole and/or sour cream. Enjoy!Note: If you have any leftovers, properly store in an airtight container in the refrigerator and use within 2 to 4 days, reheating when ready to enjoy.