1. 1. Prep your ingredients: thinly slice ribeye steak (partially freeze for 15-20 minutes for easier slicing). Thinly slice the onion. Shred cheeses if using blocks.

2. 2. Cook the steak: Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add steak in a single layer, cook 1-2 minutes per side until browned. Season with salt and pepper. Remove and set aside.

3. 3. Sauté the onions: Reduce heat to medium. Add a splash more oil if needed. Add sliced onions, cook 5-7 minutes until caramelized, stirring occasionally.

4. 4. Combine filling: Return steak to pan with onions, mix together. Remove from pan and set aside in a bowl.

5. 5. Assemble quesadillas: Wipe skillet clean. Place one tortilla in the skillet over medium heat. Sprinkle half the tortilla with a mix of provolone and mozzarella.

6. 6. Add filling: Spoon about a quarter of the steak and onion mixture over the cheese on one half of the tortilla.

7. 7. More cheese: Top filling with another layer of shredded cheese.

8. 8. Fold and cook: Once bottom cheese starts melting, fold empty half over filled half. Press gently with spatula.

9. 9. Brown to perfection: Cook 2-3 minutes per side until golden brown and crispy, and cheese is melted. Use butter or oil if needed to crisp.

10. 10. Repeat and serve: Remove, slice into wedges, serve immediately. Repeat with remaining tortillas and filling.