heart shaped biscuits

sually do something heart shaped for valentines day and this year I decided to go down the edible route! I am loving this wonderful baking cookery book, "The Hummingbird bakery cookbook" - everything is lovely from this book and the sugar biscuits were no exception! here is the recipe...
200g unsalted butter
280g caster sugar
1/4 teaspoon vanilla extract
1 egg
400g plain flour
1/2 teaspoon of cream of tartar
Icing sugar and lemon juice for the icing.
preheat the oven to 170 c
Put the butter, sugar and vanilla essence together in a mixer and cream until light and fluffy. Add the egg and mix well. Add the flour, salt and cream of tartar, and mix well, but do not over mix. The dough should be light, soft and easy to handle. Roll and cut out the shapes that you want and bake for about 10 minutes. When cool, cover biscuits with royal icing using a variety of colours and fancy sugars.