Step 1

Preheat the oven to 200 degrees.

Step 2

Heat the olive oil in a large skillet. Add the onions and peppers and saute until starting to soften, about 4-5 minutes. Add the ground beef and cook until browned. Drain any excess oil off the pan.

Step 3

Transfer the beef to a plate or bowl, and wipe out the skillet. Line up your tortillas on a large work surface, or, if you're short on space, just do them one at a time. Spread about 1/2 cup of cheese on each tortilla, covering the entire surface. Divide the ground beef evenly between the tortillas, spreading it on one half of each tortilla.

Step 4

Melt a pat of butter in the skillet and place the tortilla face up in the center. Cook on medium heat until well browned, then use a spatula to fold the cheese-only side over the beef side. Press down slightly to get the cheeses to melt together. Remove from the skillet and place on a wire rack in a 200 degree oven to keep warm. Repeat with remaining quesadillas.