In a large bowl, whisk together flour, cinnamon, nutmeg, ginger and salt. Add cold butter and work into flour mixture with your hands until butter pieces are quarter-sized.

Add molasses and ⅓ cup cold water. Mix until dough is hydrated. Add more water 1 tbsp at a time as needed. You want the dough to come together when pressed.

Turn dough out on to a lightly floured surface. Roll into a 12” square, fold dough in half, and then in half again. Wrap in plastic wrap and refrigerator for at least 30 minutes.

In a small bowl add gingerbread filling ingredients and mix to combine. Set aside for later.

Cut dough in half and roll each half into an 8”x12” rectangle. Cut rolled dough into 4 long pieces approximately 3” wide by 8” long.

Create egg wash mixture by combining egg and water, mix to combine.

Place a 2 tbsp gingerbread filling in the middle of the bottom part of each rectangle, leaving a ½-inch border around it. Brush egg wash around it, then carefully fold over the top part, using a fork to press the edges to seal tightly.

Transfer the toaster pastries to a parchment paper lined baking sheet and transfer to the refrigerator for 30 minutes so they can firm up.

Preheat the oven to 425ºF.

Remove the pastries from the refrigerator and brush them with the egg wash.

Bake the pastries for 12-15 minutes, or until golden. Let them cool for 5 minutes, then transfer to a cooling rack so they can cool completely before frosting.

While the pastries cool make the frosting. In a medium bowl, whisk together the powdered sugar, spices, vanilla, and 2 tbsp milk until smooth. If your frosting is too thick, thin with 1-2 tablespoons additional milk.

Spoon a thin layer of the frosting on top of the cooled pop-tarts. Place on a baking sheet and allow the pop tarts to harden, uncovered for about 2 hours. Store in an airtight container for up to 3 days.