Process together flours, sugar, and butter until crumbled. Then add egg and process again until doughy
Wrap that dough in plastic wrap in a disc shape and refrigerate at least 30 min
Lay out parchment paper, sprinkle with tapioca flour, place dough down, another piece of parchment paper on top and roll out into a rectangle
Use a pizza cutter to remove edges so it's straight and cut into 10 rectangles
Move that parchment paper to a baking sheet, then place in the fridge
Meanwhile take two piping bags or 2 ziplock bags, cut off the ends, and fill one with jam and one with peanut butter
Line the center of half your pop tart squares
Place other halves of dough on top, and press edges down with a fork. Poke a few holes in the top
Bake at 350 for 20 min and then cool completely
Mix icing ingredients together, spread on top of pop-tarts and enjoy!
Keep stored in the fridge