Add the gluten free flour, preferably Cup4Cup, baking powder, and kosher salt to the bowl of the food processor.

Slice the cold butter into pieces (about tablespoon size or walnut halves) and add to the dry ingredients.

Quickly pulse the butter 2-3 times.

Add the cold sour cream and pulse another 2-3 times quickly until the butter pieces are the size of peas.

Transfer the dough for gluten free pop tarts to a large bowl and with your hands bring the dough together.

Transfer it to a parchment-lined sheet tray and shape it into a rectangle.

Cover the gluten free pie dough with some plastic wrap and refrigerate for 10-15 minutes.

Roll the dough into a rectangle about ¼ inch (6mm) thick.

Fold the top third of the dough down to the center, then fold the bottom third up over the top.

Rotate the dough 90 degrees and repeat the rolling and folding process.

Refrigerate the gluten-free dough for 15 minutes, then repeat the rolling and folding process two more times.

Chill the dough for at least 30 minutes before using.

Create an egg wash by whisking an egg with a small amount of milk or water.

Roll out the dough into a rectangular shape using a rolling pin.

Cut the dough into rectangles that measure approximately 3x4 inches.

Brush the edges of the dough rectangles with the egg wash and add a generous amount of homemade blueberry jam in the center.

Place another dough rectangle on top of the filled one and gently press the edges together to seal.

Use a fork to crimp the edges together and seal the hand pie.

Place the pop tarts on a baking sheet lined with parchment paper.

Cover them and refrigerate (or freeze) for at least 30 minutes before baking.

Preheat the oven to 425F.

Brush the hand pies with the remaining egg wash and sprinkle generously with coarse sugar.

Bake the pop tarts at 425F for 10 minutes, then reduce the temperature to 365F and continue baking for another 15 minutes.

Let the homemade gluten-free hand pies cool for at least 20 minutes before serving.