For the cookies:

1. Prepare the dough:
   • In a medium bowl, whisk together the flour, baking powder, and salt.
   • In a large bowl, beat the softened butter and sugar until light and fluffy. Add the egg, vanilla extract, and almond extract (if using). Mix until combined.
   • Gradually add the dry ingredients to the wet ingredients, mixing until the dough comes together.
2. Chill the dough:
   • Divide the dough into two disks, wrap in plastic wrap, and refrigerate for at least 1 hour.
3. Roll and cut:
   • 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 ¼-inch thickness. Use a mitten-shaped cookie cutter to cut out shapes and place them on the prepared baking sheets.
4. Bake:
   • Bake the cookies for 10-12 minutes, or until the edges are just starting to turn golden. Let cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.

For the royal icing:

5. Make the icing:
   • In a large bowl, beat the powdered sugar, egg whites (or meringue powder + water), and vanilla extract until the icing is thick and glossy. Add water, 1 teaspoon at a time, to reach your desired consistency for piping or flooding.
6. Decorate:
   • Divide the icing into bowls and tint with food coloring as desired.
   • Use a piping bag with a fine tip to outline the mittens, then flood the inside with thinned icing. Decorate with festive patterns like snowflakes, polka dots, or stripes.