Sheet pan cheeseburger quesadillas are a fun mash-up of classic cheeseburgers and quesadillas! Everything is cooked on two sheet pans for easy clean up.
Preheat the oven to 425ºF (220ºC). Have two baking sheets ready and line one with parchment paper. Place the oven racks in each third of the oven.
Toss the onion and red pepper with the olive oil in a bowl. Spread them onto the parchment paper-lined baking sheet. Place the sheet in the oven on the top rack and cook them for 10 minutes.
While the onions and peppers are roasting make the burger patties. Cut 8 parchment paper squares, about 6-inches (15-cm) in size. Divide the ground beef into four portions (approximately 113g each). Roll each portion of ground beef into a ball. Place a parchment paper square on a work surface and top it with a ball of ground beef. Place another parchment square on top of the beef and press down gently with your hand to flatten the beef slightly. Use a heavy bottomed pot, or cast iron skillet to then press the beef as thin as you can. Peel away the top layer of parchment paper and place the flattened beef patty, still on the bottom parchment square, on the second baking sheet. Repeat the process with the remaining three balls of ground beef. Don’t worry if the patties overlap a bit on the baking sheet, and feel free to trim the parchment paper around each patty if you need. Sprinkle the salt and pepper evenly over the four uncooked burger patties.
Move the onions and peppers to the bottom rack of the oven and place the burgers on the top rack. Cook the beef patties for about 6 to 8 minutes, or until the internal temperature of the beef is 165ºF (74ºC). Keep an eye on the vegetables and remove them from the oven if they begin to char.
once the burger are cooked through, top each burger patty with a cheese slice then place them back in the oven for 30 seconds to 1 minute to let the cheese melt. Remove the burgers from the oven.
Scoop the onions and peppers back into the bowl in which you mixed them with the oil. Place four of the tortillas on the baking sheet the vegetables were cooked on. Top each tortilla with a burger patty (parchment paper removed), and then cooked onions and peppers. Place a second tortilla on top of each burger and place back in the oven for 3 to 4 minutes, or until the tortillas begin to toast. Remove the quesadillas from the oven and carefully slice them into wedges. Serve with more onions and peppers if you like, plus your favourite burger and quesadilla condiments. I like to serve them with burger sauce, pickles, guacamole, and fresh salsa.