Pierce the sweetpotato a few times with a fork and microwave until soft, 7 to 10 minutes.
Cool slightly, remove the skin and mash the flesh with a fork.
Set aside
Heat 1 tablespoon of the butter in a large nonstick skillet over medium-high heat. Add the pork, chile powder and kosher salt. Cook pork, breaking up the meat, until browned, about 3 minutes.
Add garlic, sweetpotato and scallions to the pan with the ground pork and cook, stirring, 2 more minutes, add the cilantro; taste and add salt if necessary.
Transfer the mixture to a bowl and set aside.
Preheat the oven to 200 degrees.
Wipe out the skillet.
Add 1/2 tablespoon of butter to to the skillet, melt over medium-high heat and swirl to coat the pan.
Lay a tortilla in the skillet.
Spread one-quarter of the pork mixture on one half of the tortilla.
Sprinkle 1/2 cup cheese over the pork.
Fold the plain half of the tortilla over the filling and cook until the quesadilla is golden, 1 to 2 minutes per side.
Transfer quesadilla to a baking sheet and place in the oven to keep warm.
Repeat procedure to make 3 more quesadillas.
Cut each quesadilla into wedges and serve with pickled jalapenos and sour cream, if desired.