Make the dough: whisk together the flour, sugar, and salt. Add in the cold cubed butter and cut in using a pastry cutter or forks until it forms pea-sized crumbles. Whisk together the egg and milk and add to the dough, mixing until it clumps together.

Roll out the dough on a floured surface and form into two discs. Wrap in plastic wrap and refrigerate for at least 2 hours.

Take a disc of dough from the fridge and roll into a 9x12 inch rectangle. Cut into 3x4 inch rectangles for the pop-tart bases.

Place the rectangles on a lined baking sheet and refrigerate. Repeat with the second disc.

Make the filling by combining brown sugar, cinnamon, and flour. Brush the prepared rectangles with egg wash and add the filling.

Top with another rectangle, seal the edges, and poke holes in the tops.

Refrigerate for 20 minutes, then preheat your oven to 350°F.

Bake the pop-tarts for 22-26 minutes until golden.

Make the glaze by whisking together the glaze ingredients, and apply to cooled pop-tarts.

Store in an airtight container for 3 days or in the fridge for a week.