In a large bowl combine the butter and sugar. Mix until well combined.

Stir in the egg and mix well. Stir in the vanilla.

Add the flour, baking powder, and salt to the bowl. Mix for 2 minutes or until well combined.

Place the dough in plastic wrap, cover completely, and refrigerate for at least 1 hour or up to 3 days.

When ready to bake preheat the oven to 375 degrees.

Sprinkle an area with flour and roll out the dough to 1/4 inch thickness. Cut out leaf shapes. Place on a cookie sheet, 2 inches apart, and bake for 7-8 minutes.

Keep a careful eye out on the cookies as you do not want them to brown.

Cool on the cookie sheet for 2 minutes then remove to a wire rack to cool completely.

To make the icing combine the powdered sugar and meringue powder in a bowl. Add water 1 tablespoon at a time until desired consistency is reached.

Divide into 3 bowls. Color 1 bowl red, 1 orange, and 1 yellow.

Put half the icing into zip top baggies. Snip off a corner of the baggie and pipe an outline onto each leaf. Fill in the leaf with remaining icing. Allow icing to harden for 30 minutes.

Using the icing still in the baggies, pipe on "veins" inside the cookies, doing 1 at a time, and quickly sprinkle with sanding sugar. Continue until they are completed.