1. Make the cookie dough:

• In a medium bowl, whisk together the flour, baking powder, and salt.
• In a large bowl, beat the butter and sugar together until light and fluffy, about 2–3 minutes.
• Mix in the egg, vanilla extract, and almond extract (if using). Gradually add the dry ingredients, mixing until just combined.

2. Chill the dough:

• Shape the dough into a disk, wrap it in plastic wrap, and refrigerate for at least 1 hour.

3. Roll and cut the cookies:

• Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.
• Roll out the chilled dough on a lightly floured surface to about 1/4 inch thickness. Use a Christmas tree-shaped cookie cutter to cut out cookies and place them on the prepared baking sheets, spacing them about 1 inch apart.

4. Bake the cookies:

• Bake for 8–10 minutes, or until the edges are just lightly golden. Cool the cookies on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

5. Prepare the royal icing:

• In a large bowl, beat the powdered sugar, egg whites (or meringue powder mixture), and vanilla extract until smooth and slightly thickened, about 2–3 minutes. Add water 1 teaspoon at a time to reach your desired consistency.
• Divide the icing and tint one portion green with gel food coloring for the trees.

6. Decorate the cookies:

• Using a piping bag with a fine tip, outline and fill the tree-shaped cookies with green icing. Add sprinkles or edible glitter while the icing is still wet to mimic ornaments.
• Place a star-shaped candy or sprinkle at the top of each tree. Allow the icing to set completely before serving or packaging.