In a mixing bowl, combine gluten-free flour, cold butter, sugar, egg, vanilla extract, matcha powder, and salt. Mix until a dough forms.

Wrap the dough in plastic wrap and refrigerate for 30 minutes.

Preheat the oven to 350°F (175°C).

Roll out the dough on a floured surface and cut into rectangles.

Place a spoonful of fruit jam in the center of half the rectangles, then top with the remaining rectangles. Seal the edges with a fork.

Place the pop tarts on a baking sheet and bake for 20 minutes or until golden brown.

In a bowl, whisk together powdered sugar, milk, and matcha powder until smooth.

Drizzle the glaze over the cooled pop tarts.