Bring a pot of water to a simmer. Add the pierogies and simmer until slightly soft, 5 to 7 minutes. Drain and pat dry.
Preheat the oven to broil.
Heat a 12-inch ovensafe nonstick skillet over medium heat. Add the butter and heat until foaming. Saute the pierogies until golden brown, 4 to 5 minutes a side. Remove from the heat.
Evenly sprinkle a layer of the sauerkraut on top of the pierogies. Then add a layer of the Swiss and finally, an even layer of the corned beef.
On the lowest rack, broil the mixture in the skillet until the cheese and corned beef are golden brown and the cheese is bubbly, 2 to 3 minutes. Garnish with the caraway seeds and minced chives. Serve with a squirt of 18,000 Island Dressing.
Mix the mayo, gochujang, jalapenos and mustard in a small bowl.