Here's the steps on how to make the quesadilla empanada style:
1) Butter one side of the tortilla and place the buttered side on a plate (or directly onto a pan).
2) Spread some shredded cheese on one half side of the tortilla, making sure the cheese comes out to the very edges of the tortilla; the cheese will serve as sealing agent as they melt.
3) Top the cheese with the chicken, red and green peppers and red onion; cover with more cheese.
4) Bring the other half of the tortilla over to the filled part, like empanada. (At this point the edges won't seal together)
5) Heat a non-stick frying pan or cast iron pan; do not oil the bottom of pan.
6) When pan is hot but not smoking hot, slide the filled tortilla into the pan and grill each side pressing down the edges to seal. It's the melting cheese that will make the edges to seal up.