Warm it up: Preheat your oven to 200°F to keep quesadillas toasty.

Sauté veggies: In a large skillet, heat olive oil over medium heat. Sauté onions and bell peppers until they begin to soften, about 4-5 minutes.

Brown the beef: Add ground beef to the skillet, sprinkle with taco seasoning, salt, and pepper, and cook until browned. Drain any excess grease.

Cheese it up: Lay out tortillas and evenly distribute cheese on each, followed by the beef mixture on one half.

Cook quesadillas: Melt butter in the skillet over medium heat. Place a tortilla in the skillet, cook until golden, then fold and press to seal the cheesy goodness.

Keep warm: Transfer cooked quesadillas to the preheated oven on a wire rack to stay warm while you cook the rest.