Recently I made them for toppers to my Pi day banana cream jar pies https://www.instructables.com/id/Banana-Cream-Jar-Pies/, and other pics from different cookies, we love snacking on these buttery, flaky cookies, that I like topping with demerara (raw) sugar for some crunch.
Pie dough, here I had leftover dough from half a 9-inch pie (my recipe is this one: https://www.instructables.com/id/Pumpkin-Pie-20/
1/3 cup finely ground vanilla wafer cookies, from about 12 cookies (optional, they add sweetness and some texture, since I used the vanilla wafers in the jar pies, I wanted the same flavors for the cookies, you can use graham cracker crumbs, animal cracker crumbs, gingersnaps, etc. If you don't use crackers, you'll need some AP flour to roll out the dough)
Step 2: Roll Out Dough, Cut Into Shapes, Egg Wash, Bake, and Enjoy
Put 1/4 of the vanilla wafer crumbs (or some AP flour) on work surface, top with pie dough, top with 1/4 more crumbs and roll out dough. Halfway through rolling coat the top and bottom each with the remaining half of the vanilla wafer crumbs and continue rolling until dough is about 1/8-inch thick.
Cut into desired shapes, for Pi day I cut out as many numbers of pie as I had room on the baking sheet. Pie dough tends to toughen with rolling, so I would only roll the extra scraps once more to get more cookies. Place cut-outs on a parchment-lined baking sheet. Refrigerate, or freeze, about 20 minutes to firm up.
Mix the egg white with 1 Tbsp. water and stir well. Use a pastry brush to coat cookies with egg wash. Sprinkle with demerara sugar. (You could also sprinkle with cinnamon sugar.)
Bake, until golden brown and crisp. The small ones take around 15-20 minutes, larger cut-outs will take longer, rotate the baking sheet front to back halfway through baking. Transfer to cooling rack, let cool to room temperature.
Use as decoration for cream pies, eat with pudding, ice cream, whatever you like, or simply eat them as is, happy Pi day, enjoy!
Pie dough cookies stored, covered, at room temperature can be kept up to three days.