In a food processor, add flour, sugar and salt and pulse to combine. Add butter, cut into 1 inch pieces, and pulse until it looks like coarse meal with no large chunks remaining. Add vinegar and water and pulse until the dough starts to come together. Place on floured surface and knead until all flour is incorporated, it won’t be smooth. Wrap in plastic wrap and refrigerate for at least 2 hours.

Roll crust into a 12 x 18 inch rectangle and divide into six 6-inch squares. If dough gets to warm, place in freezer for a few minutes.

In a small bowl, combine brown sugar, cinnamon, salt and nutmeg. Scoop out a bit of the peach half so that you have room for more filling. Place half a peach into the center of each square and fill with the filling. Top with butter.

Bring the corners together and pinch the seams to seal. Place in a butterd 9 x 13 inch baking dish and chill for 30 minutes.

Preheat oven to 375º. Whisk together the egg and 1 tablespoon of water. Brush over the tops and sides of the dumplings. Bake for 30-40 minutes until they are golden brown.

While the peaches are baking, beat butter, powdered sugar and bourbon together until smooth. When the peaches have been removed from the oven, spoon the sauce over the top so that it melts down the sides.