Prepare the dough by mixing flour and cold butter until crumbly. Add a pinch of salt and enough cold water until cohesive. Wrap in plastic wrap and chill for 30 minutes.

Make the filling by combining brown sugar and cinnamon in a bowl.

Roll out chilled dough to 1/8 inch thick on a floured surface, then cut into rectangles.

Assemble by placing one rectangle on a baking sheet, adding one tablespoon of filling in the center, topping with another rectangle, and sealing edges with a fork.

Preheat oven to 375°F (190°C). Bake pop tarts for 20-25 minutes until golden brown.

For frosting, whisk powdered sugar with milk until smooth; drizzle over cooled pop tarts.