Make the mini pop tarts first so that they have time to bake and cool. Start by making the dough first. Mix 1 cup flour and 1/4 tsp salt together in a large bowl. Cut 5 Tbsp of cold, cubed butter into the flour with a fork or pastry cutter until the mixture has pea-sized crumbles of butter. Slowly drizzle in 3 Tbsp of ice-cold water, 1 Tablespoon at a time. Stir with a large spatula after every Tablespoon of water that you add. Be careful not to add more water than you need to and stop when the dough begins to clump.
Flatten the dough out on a floured surface into a 1-inch thick disc with your hands. Wrap it tightly in plastic wrap and chill in the fridge for at least 2 hours (or up to a week).
While the dough chills make the brown sugar pop tart filling. Mix 3 Tbsp Domino ® Light Brown Sugar, 3/4 tsp cinnamon, and 1 tsp flour together in a small bowl. Set aside.
Remove the chilled dough from the refrigerator and let it sit at room temperature for 10 minutes to make it easier to roll and work with. Unwrap the dough and place it on a lightly floured work surface. Roll the dough out until it's about 1/8 inch thick. Cut the dough into small rectangles that are 1 x 1.25 inches. You should end up with at least 24 rectangles.
Place half of the rectangles about 1 inch apart on a baking sheet lined with parchment paper or a silicone baking mat. Brush the rectangles with an egg wash (1 large egg mixed with 2 tsp milk), then place a tsp of the brown sugar filling in the center of each rectangle. Place the remaining pastry dough rectangles on top of the filling and seal the edges of each little pop tart with a small fork.
Brush the top of the pop tarts with egg wash, then use a small fork to poke holes in the tops of each pop tart to let steam escape while they bake.
Chill the pop tarts in the fridge for 15 minutes, then bake them at 350 F/175C for 15-17 minutes, or until they're golden brown. Let the pop tarts cool on the pan for 5 minutes, then transfer them to a wire rack to finish cooling.
As the pop tarts cool, make the cinnamon glaze. Whisk together 1 cup of Domino ® Powdered Sugar, 1 Tbsp milk, 1 tsp ground cinnamon, and 1/4 tsp vanilla extract. It should be thick, but not hard to spread. If it seems too thick, add another tsp of milk to thin it. If it seems too thin, add another Tbsp of Domino ® Powdered Sugar to thicken it.
Once the pop tarts are fully cooled, use a small spoon to top each pop tart with glaze. Sprinkle a garnish of Domino ® Turbinado Sugar over the glaze, then set the pop tarts aside to let the glaze firm up. Cover the remaining glaze with plastic wrap to prevent it from crusting and set aside.
If you make the mini pop-tarts in advance, they can be stored in an airtight container at room temperature for 3 days.