In a small bowl, combine the jalapeño, cream cheese, cheddar cheese, garlic, and cumin. Mix well.

Divide the beef into eight pieces; shape into patties about the same diameter as your rolls, pressing the centers very thin but leaving a 1/4-inch ridge around the edges. Divide the filling evenly between four patties, spreading it evenly to fill the center of the burger. Top with the remaining 4 patties, flipping them over so the thin center forms a pocket over the filling. Press the edges to seal.

Heat a grill pan over medium-high heat until very hot. Reduce heat to medium-low. Place the burgers in the pan and cook for 5-6 minutes on each side, or until cooked through. If desired, top with additional cheddar cheese.

Serve on rolls with lettuce and thinly sliced red onion.