1. Heat the oven to 400 degrees and line a baking sheet with parchment paper.
2. On a floured surface, roll out a piecrust to a 1/8-inch thickness. Trim it to make three 2 1/2-by-10-inch strips. Gather the scraps and reroll the dough to cut a fourth strip. Repeat with the second crust.
3. With a pastry brush, coat each strip with egg white. Spread on the jam or chocolate filling, leaving about 3 inches of space at the top and 1/2 inch at the sides and bottom.
4. Fold the dough up over the filling and secure it about 1 1/2 inches from the top edge. Seal the edges of the folded portion by pressing them with the back of a fork. Brush the top of each pie with egg white, then transfer the pie to the baking sheet.
5. Bake the pies until their edges are just beginning to brown, about 10 minutes. Let them cool on the baking sheet for 3 minutes, then move them to a rack to cool completely.
6. Meanwhile, tint the frosting with food coloring. To make the faces, scoop the frosting into ziplock bags, seal them, and make a tiny snip in one corner of each. Pipe features onto the vanilla wafers.
7. Frost the cooled pies as desired. Set the vanilla wafers in place and pipe on frosting hair.