Pop Tarts

1. In the bowl of an electric mixer fitted with the paddle attachment, beat together butter and sugar until well combined. Add half of egg, reserving other half for later, and mix, scraping down the sides of the bowl as necessary. Set aside.
2. In a medium bowl, combine all of the flours. With the mixer on low speed, add flours into the creamed mixture all at once; mix until well combined.
3. Turn dough out onto work surface and form into a disk. Wrap with plastic wrap and refrigerate until chilled, about 3 hours.
4. Once dough is chilled, preheat oven to 350°F.
5. Place dough on a floured work surface and roll out to 1/8-inch thick. (Here’s the tricky part. The dough needs to be warm enough to manipulate but cold enough to hold its shape. Frequent, but quick trips back into the the freezer are necessary.) Cut out into 10 even rectangles, about 3″ x 4″ each.
6. Place 5 of the tart rectangles on a baking sheet. Fill with jam, about 1 heaping tablespoon per tart, leaving half an inch of clearing space around the outer edges of the rectangle. Carefully place another tart rectangle on top and press with a fork around the edges to seal. Trim away any extraneous dough. Repeat with the remaining tart rectangles and jam. If dough begins to crack, dip your finger in water and smooth it out. Works like magic. Brush tarts with the reserved 1/2 of a beaten egg. Sprinkle with turbinado.
7. Transfer to the freezer for 10 minutes. (This helps the dough to hold its shape.)
8. Bake in the preheated 350F oven for 15 to 20 minutes, or until golden brown. Allow to cool before serving. Reserve leftovers in an air tight container.