• Grease a 9×13 baking dish and set aside.

  In the bowl of a stand mixer fitted with a whisk attachment, combine the gelatin and 1/2 cold water. Set aside to "bloom".
• In a medium saucepan, combine the white sugar, corn syrup, salt, and 1/2 cup water.
• Attach a candy thermometer to the side of the pan (make sure the thermometer is submerged in the liquid but not touching the bottom), and heat over medium-high heat until the mixture reaches 240° – about 10 minutes.

  *You can swirl the pan occasionally, but don't stir it much – it can cause the sugar to crystalize.
• When the sugar mixture reaches 240°, remove from the heat.
• With the mixer on low speed, slowly pour a thread of the sugar mixture down the side of the mixing bowl into the gelatin mixture. (If you add the hot mixture to the gelatin too quickly, it will "cook" the gelatin and the marshmallows won't set up well.)
• Once all of the sugar mixture has been added to the gelatin, beat on high speed until the mixture is very thick and forms stiff peaks – about 15 minutes. Then add the vanilla and mix thoroughly.
• Pour the marshmallow mixture into the prepared pan and smooth the top.
• In a small bowl, combine the powdered sugar and cornstarch then, using a sifter or sieve, generously sprinkle over the top of the marshmallows. (Save the leftover sugar/cornstarch mixture for later.)
• Allow the marshmallows to sit, uncovered and at room temperature, for 4-6 hours or overnight.
• Once the marshmallows are completely set, dust a knife with the leftover powdered sugar/cornstarch mixture and cut the marshmallows into bite-sized squares.
• Remove the cut squares and roll them in the sugar/cornstarch mixture so they are thoroughly coated – this will keep them from sticking together.

Dough:

• In a bowl, melt the butter. When melted, add the water to the butter.
• In another bowl, measure out the flour.
• Add the butter, water, eggs, and salt to the flour and stir until combined.
• Knead until smooth and pliable but don't overknead – about 5 minutes.
• Form into a ball and allow to rest for 30 minutes.

Bacon Topping:

• Cut the bacon into 1/2" cubes and fry up. Crumble, cool, and set aside.

Cheesy Potato Filling:

• While the dough is resting, you can prepare the filling.
• Wash and cube the potatoes then bring them to a boil in a pot of salted water and cook until tender.
• While the potatoes are cooking, dice the onions and saute them in the butter. Set aside when cooked.
• When the potatoes are cooked, drain, then add half of the onions (reserve the rest for topping), and the shredded cheese and mash.
• Set aside and allow to cool.

Preparing the Pierogi:

• Roll the dough out to 1/8" thick and cut the dough into 3" circles (a jar lid works well if you don't have a biscuit cutter).
• Working with one circle at a time, place about a Tbsp of filling in the center, then fold the dough over and pinch the edges shut, making somewhat of a crescent shape.
• Place the completed pierogi on a cookie sheet.

  *If you're not cooking them immediately, you can freeze them (they cook perfectly straight from the freezer). Once frozen, transfer to a ziploc bag.

Cooking the Pierogi:

• *Close to serving time, reheat the bacon and sauted onions in a frying pan and set aside.
• Bring a large pot of water to a boil. (The wider the pot the more pierogi you can cook at once.)
• Add one layer of pierogi and cook for 3-5 minutes, or until cooked. After a couple minutes, they should float to the top, then need to cook for another couple minutes.
• Remove from the pot with a slotted spoon.
• You can either eat them just boiled or you can place the boiled pierogi in a frying pan with butter and saute them for a minute to give them a crisp edge.
• Remove and serve. Top with sour cream, bacon, and onion.