Make the cookie dough

Cup of Yum
1. Preheat the oven to 350F (180C). Combine the flour, baking powder and salt in a bowl.
2. Put the butter, sugar and vanilla in the bowl of your stand mixer or a large mixing bowl. Beat together for at least three minutes, stopping halfway to scrape the bottom and sides of the bowl. 
3. Add the egg and beat until incorporated.
4. Gradually add the flour, a little at a time, mixing it in until the dough comes together. You can mix in the last of the flour using your hands if needed.
5. Turn the dough out onto your worktop and use your hands to gently knead the dough until you have a pliable, non sticky, cookie dough the consistency of Play Doh. Divide the dough into three chunks, keeping any dough you are not using covered with plastic wrap to keep from drying out.

Roll out dough and cut out cookies

1. Lightly dust your liner or baking parchment with a little flour. Use your rolling pin with ¼ inch rings to roll out the dough.
2. Cut out the cookies and transfer the liner (or paper) onto a heavy baking sheet, spacing the cookies slightly apart. Repeat with the rest of the dough, gathering and using any scraps and bake the cookies in batches.

Bake the Cookies

1. Bake for 6-8 minutes for smaller cookies and 9-11 minutes for slightly larger ones. The cookies can be baked less time for softer texture and a little longer for a crisper texture.
2. Carefully transfer the cookies to a wire rack to cool.

Royal Icing

1. Put the egg whites and cream of tartar in the bowl of your stand mixer. Start whisking on low speed until frothy.
2. Increase the speed and once the egg whites form soft peaks, start adding the icing sugar one tablespoon at a time. Continue to whisk until the icing drops slowly off a spoon. Always keep the royal icing covered otherwise it will quickly dry out.
3. If the icing is too thin you can add more icing sugar. If too thick, thin it with a little water or lemon juice.

Decorate the cookies

1. Put the royal icing in a piping bag and snip a very small hole at the tip (or use a silicone bottle as I have done).
2. If you wish to fill (flood) the cookies, thin half of the icing with a little water and use it to fill an outlined cookie – pushing the icing to the edges using a toothpick. Leave to dry completely at room temperature.

Simple Icing

1. Put the icing sugar in a bowl and gradually add enough water until you have a thick glaze that drops slowly off a spoon. Stir in the vanilla if using. Use this glaze to decorate the cookies leaving it to dry completely before storing them.