Make the pie dough. In the bowl of a food processor, blend together the flour with shortening and salt until the mixture resembles coarse sand. Add the egg yolk and buttermilk and mix just until the dough comes together. Alternatively, mix the dough by hand. Divide the dough in half and wrap in plastic wrap. Chill in the fridge for at least one hour or until firm.
Meanwhile, prepare the fillings. Beat together the softened mascarpone with cream cheese, 2 tablespoon granulated sugar, egg yolk, and vanilla bean paste in a medium bowl until well combined.
Peel and dice enough peaches to yield 2 cups. Gently toss the peaches with the cornstarch and brown sugar in a medium bowl. Let sit for 10 minutes.
Lightly dust a clean work counter with flour. Roll out the pie dough until it's ⅛ inch thick. Cut out 3 ½-inch round circles with a biscuit counter. Place 1 tablespoon of the cream cheese filling in the center of half of the circles followed by 1 tablespoon of the peaches. Try not to add too much of the liquid from the peaches or the pastry can get soggy.
Place a cut circle dough on top of the filled ones and use a fork to seal the edges. Place on a lined baking sheet and repeat with the remaining dough. Keep the pies in the fridge while the oil heats.
Preheat frying oil to 350 degrees F.
Combine 2 tablespoon sugar with 1 teaspoon cinnamon in a small bowl.
Carefully fry the hand pies a couple at a time until they turn golden brown, about 4-5 minutes. Remove the pies with a slotted spoon and drain the excess oil on paper towels. Sprinkle the cinnamon sugar on top and repeat with the remaining hand pies. Serve warm.