In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream together the vegan butter and granulated sugar until light and fluffy.

Add the unsweetened applesauce and vanilla extract to the butter-sugar mixture. Mix until well combined.

Gradually add the dry flour mixture to the wet mixture, mixing until a dough forms. The dough will be crumbly, but it should hold together when you knead it gently with your hand.

Divide the dough in half, form each half into a disk, wrap in plastic wrap, and refrigerate for at least 1 hour or until firm.

Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper.

On a lightly floured surface, roll out one disk of dough to about ¼ inch thickness. Use cookie cutters to cut out desired shapes.

Place the cut-out cookies on the prepared baking sheets, leaving a bit of space between them.

Bake for 10-12 minutes, or until the edges are lightly golden. Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.

Once the cookies are completely cool, prepare the vegan royal icing according to the instructions.

Transfer the icing to piping bags fitted with small round tips or your desired decorating tips.

Outline the cookies with the icing, and then fill in the outlines with more icing.

Use toothpicks or a small, clean paintbrush to help spread and smooth the icing into the desired areas.

Decorate with additional sprinkles, edible glitter, or other decorations as desired.

Allow the icing to set and harden before serving or packaging the cookies.