Preheat oven to 375F. Line a large baking sheet with parchment paper; set aside.

In a large mixing bowl, mix the butter, brown sugar, and granulated sugar together with an electric mixer, just until blended (do not over-mix).

Add the molasses, egg, and vanilla and mix until incorporated.

In a separate bowl, whisk together the flour, cinnamon, ginger, all spice, and salt. Add the dry mixture to the wet and mix with the electric mixer until a crumbly dough forms.

Turn the dough out onto a sheet of parchment paper and press the dough into a ball. Place another sheet of parchment paper on top of the dough and use a rolling pin to roll the dough out to ¼-inch thickness (the dough should be just slightly thinner than the cut out area of the cookie cutter where the cookies will interlock. If the dough is too thick the cookies will not interlock to form the trees).

Use a 3D Christmas tree cookie cutter to cut the trees out of the dough. Transfer the trees to the prepared baking sheet.

Bake the cookies at 375F for 9-10 minutes until set. Cool on the baking sheet for 2-3 minutes, then use a spatula to transfer to a wire cooling rack to cool completely to room temperature.

Use royal frosting and sprinkles to decorate the cookies.

In a medium mixing bowl, beat together the water, meringue powder, and vanilla extract with an electric mixer on medium speed until soft peaks form.

Add the powdered sugar and mix on low speed until soft peaks form.

If desired, add food coloring and mix well.

Use the frosting immediately to decorate cookies, then allow to air fry until fully set, about 1-2 hours.