In a skillet over medium heat, add the ground beef and diced onion. Cook until the beef is browned and the onion is translucent, about 7-10 minutes. Break up the beef with a spatula as it cooks to ensure even browning.
Once the beef is fully cooked, drain any excess fat. Add chili powder, dried oregano, salt, garlic powder, and cumin to the skillet. Stir well to combine all the ingredients, and cook for an additional 2-3 minutes until fragrant.
Lay out the tortillas on a flat surface. Divide the beef mixture evenly among the tortillas, placing it on one half of each tortilla. Feel free to sprinkle some shredded cheese on top of the beef for that extra cheesiness.
Fold each tortilla in half over the filling. In the same skillet, melt 1 tablespoon of butter over medium heat. Once melted, add two quesadillas to the skillet. Cook for about 3-4 minutes on each side or until they are golden brown and crispy. Repeat with the remaining quesadillas, adding more butter as needed.
Once cooked, remove the quesadillas from the skillet and let them cool for a minute. Cut each quesadilla into wedges and serve with your favorite toppings, such as salsa, sour cream, or guacamole.
