Cut your cold butter into slices

Place flours, protein, and butter into a processor or blender and process until crumbly

Add egg and blend again until dough is achieved

Place your dough in plastic wrap, flatten into a disc, wrap, and refrigerate for 30min + (if your dough is sticky spray a silicone spatula with nonstick spray to retrieve from the processor)

Dust a surface with more flour, and roll dough into a large rectangle

Use a pizza cutter to slice into 10 rectangles

Place half those rectangles on a baking sheet lined with parchment paper

Make filling by whisking ingredients together, then spoon onto centers of dough rectangles (you may have some leftover)

Place remaining 5 rectangles overtop, seal the edges with your fingers, then a fork to fully seal edges

Use your fork to poke holes in the top

Bake at 350 for 20 min

Allow to cool 5 min, then place on cooling rack

Melt your coconut butter, then combine frosting ingredients together, and spread overtop cooled poptarts

Place in the fridge 15min+ for frosting to harden

Enjoy!