01 - Heat olive oil over medium heat in a large skillet. Add chopped onion and cook for 2 minutes until softened.
02 - Incorporate minced garlic and cook for 30 seconds until fragrant.
03 - Add ground beef and cook, breaking it up with a spoon, for 5 to 6 minutes until evenly browned.
04 - Stir in chili powder, cumin, smoked paprika, salt, and black pepper. Cook for 1 minute to release flavors.
05 - Add tomato sauce, stir thoroughly, and simmer for 2 to 3 minutes until mixture thickens slightly. Remove from heat.
06 - Wipe skillet clean and return to medium heat.
07 - Place one tortilla on a flat surface. Sprinkle a mixture of cheddar and Monterey Jack cheese evenly over half the tortilla. Spoon approximately one quarter of the beef filling atop the cheese, then add additional cheese before folding the tortilla in half.
08 - Melt a small amount of butter in the skillet. Cook the folded tortilla for 2 to 3 minutes per side until golden brown and cheese is melted inside.
09 - Continue with remaining tortillas and beef mixture, cooking each until crisp and thoroughly heated.
10 - Cut quesadillas into wedges and serve immediately topped with optional sour cream, salsa, chopped cilantro, and lime wedges.