Heat a medium skillet over medium-high heat. Add the ground beef and cook until browned. Remove from the heat and drain the grease. Stir in the taco seasoning and let cool for 10 minutes.
In a large mixing bowl, add the beef, corn, black beans, and green chilis. Stir together.
Prepare a 9x13 baking sheet by spraying it with cooking spray. Lay 2 tortillas in the middle of the pan, then continue laying 6 more tortillas around the edges, making sure half of each tortilla hangs off the edge.
Add the beef mixture and spread evenly. Sprinkle on the cheese.
Place 2 more tortillas on top of the mixture. Fold over the tortillas hanging off the edge. Melt the butter and spread it on top of the quesadilla.
Place a second pan on top of the quesadilla to hold the tortillas down. Bake in a 425º F oven for 15 minutes, then remove the top baking pan and cook for another 5 minutes, or until the tortillas are golden and crispy.
Let cool for a couple of minutes. Cut into rectangles and enjoy!