Prepare the Dough:

• In a large bowl, cream together the butter and sugar until light and fluffy.
• Add the egg and vanilla extract, beating until well combined.
• In another bowl, whisk together the flour, baking powder, and salt.
• Gradually add the dry ingredients to the wet ingredients, mixing until the dough comes together.

Shape the Cookies:

• Divide the dough into small portions and roll them into smooth balls.
• Flatten each ball slightly to create a base for the Christmas tree.

Bake:

• Preheat your oven to 350°F (175°C).
• Place the cookies on a baking sheet lined with parchment paper.
• Bake for 10-12 minutes, or until the edges are lightly golden.
• Let the cookies cool completely on a wire rack.

Decorate:

• Prepare the royal icing and divide it into two parts. Tint one part with green food coloring.
• Using a piping bag fitted with a round tip, pipe the green icing onto each cookie in a circular motion to create a tree shape.
• Add a small amount of white icing on top, if desired.
• Decorate with edible glitter, sprinkles, and finish with a star-shaped decoration on the tree’s top.