FOR THE COOKIES:

1. Preheat oven to 350°F and line two cookie sheets with parchment paper.
2. Add the butter and sugar to a large bowl. Beat with an electric mixer until smooth and creamy.
3. Add the egg and vanilla and mix until completely incorporated.
4. Sift in the flour and baking powder one cup at a time.
5. Split the dough in half. Lightly flour a rolling pin and roll both halves of dough out on a prepared surface to a thickness of 3/8 inch. No need to chill the dough. The cookies will bake better if the dough is at room temperature. 
6. Use a round cookie cutter to cut out the cookies. Arrange the cookies between two cookie sheets and bake for 6-8 minutes or until the edges are a very pale golden color. Do not over bake.
7. Remove from the oven and leave to cool while you make the royal icing.

FOR THE ICING:

1. Add the powdered sugar and meringue powder to a mixing bowl. Add 2 tablespoons of water and mix.
2. Continue to add water a tablespoon at a time until the icing runs off the beater in ribbons.
3. Transfer the icing to a piping bag then snip the end off to make a small opening. Pipe the icing on top of the cooled cookies, then use a toothpick to even out the icing. When dry, use the black writing icing to pipe two lines onto the cookies for the light’s string, add mini M&M’s on either side of each line for the lights.