Heat a large skillet over medium heat.
Combine Fiesta Ranch mix with sour cream and set aside.
For each burger, spread butter on one side of tortilla.
Put tortilla in skillet, butter side down.
Spread Fiesta Ranch mix on tortilla and sprinkle evenly with both cheeses leaving edges clean. Put some tomato, onion, bacon and jalapeno over the cheese; add the burger to one side of tortilla and fold over the shell.
When the bottom side is browned, about 45-90 seconds, flip the quesadilla over and grill the other side.