Special equipment: You'll need a piping bag fitted with a 1/2-inch plain round tip (Ateco number 806 tip works well)
For the pumpkin pie filling: Heat the oven to 300 degrees F. Grease an 8-inch cake pan with cooking spray.
In a mixing bowl, whisk the pumpkin, heavy cream, sour cream, egg, vanilla, sugar, bourbon, cinnamon, ginger, nutmeg, cardamom, salt and allspice. Pour the mixture into the prepared pan. Bake until just set, 10 to 12 minutes. The filling will be baked again inside the cookies, so be sure not to overbake here.
Remove from the oven, let cool to room temperature, then wrap and refrigerate overnight. The filling needs to be cold before using.
For the dough: Using a stand mixer fitted with the paddle attachment, mix the flour, sugar, cinnamon, nutmeg, ginger, allspice and salt until blended. Add the butter and mix on low speed until small pieces of butter are visible. Combine the cold apple juice with the vinegar and add to the flour mixture. Mix on medium speed until moist crumbles of dough form.
Scrape the dough onto a work surface and knead 6 to 8 times until the dough comes together.
Cut the dough into two equal pieces (weigh the dough if you have a scale), and shape each half into a rectangle. Don't overwork the dough.
Work with one piece of dough at a time, keeping the second piece wrapped in plastic at room temperature.
Roll out one piece of dough between two pieces of parchment into a 10-by-14-inch rectangle that's 1/8-inch thick, stopping occasionally to peel away the paper, dust lightly with flour, and flip over. Keep the rectangle neat-this will help with the cookie count. Chill the first sheet of dough, still sandwiched by the parchment. Repeat with the second sheet. Chill both for at least 1 hour or overnight.
Remove one sheet of dough from the refrigerator at a time. Peel off the top piece of parchment and trim the dough to 10-by-14 inches. (Use a ruler and a pizza cutter to trim the dough.) Cut the dough into 2-by-2-inch pieces, yielding 35 pieces. Return the cut dough to the fridge and repeat with the second sheet of dough. Chill until firm, about 1 hour.
Assemble the cookies and bake: Heat the oven to 350 degrees F and line two sheet pans with parchment. With a spatula, carefully lift the cut dough, piece by piece, onto the lined pans, 2 inches apart. Once the bottom 20 pieces are on the pans, the "pies" are ready to be assembled.
Remove the pumpkin filling from the refrigerator and spoon it into the piping bag.
Brush the edges of the dough pieces with the egg wash. Pipe a mound of filling in the center of each pie, leaving a 1/2-inch border around the edges of the dough. Carefully arrange another piece of dough over the filling, lining up the edges. Using your fingertips, lightly press around the filing, removing any air pockets as you press. Using the tines of a fork, lightly press the edges of each pie to seal.
Brush the entire top of each pie with more of the egg wash, carefully avoiding excess wash. Chill the pies until firm, about 30 minutes.
For the topping: In a small bowl, mix the sugar and cinnamon.
Remove the pies from the fridge and sprinkle each one with the cinnamon sugar. With the tip of a small knife, prick the dough, giving each pie a small air vent.
Bake until the dough feels baked and turns golden brown and the bottom of the pies are lightly golden brown, 16 to 18 minutes. Remove from the oven and let cool completely on the pans.
Store for up to 1 day in an airtight container at room temperature.