Nimble Nibbles: Piped Cookie Bars

Hi Everybody!
This week's post was a first for me; cookie bars with a marshmallow frosting! The frosting turned out amazingly, as it did taste like marshmallows but it contains no gelatin and it's dairy free (double bonus :D) The contrast between the texture of both the biscuit and the frosting worked really well together
So let's get started...

You will need:

150g butter
250g self raising flour
100g caster sugar
1 egg
1tsp vanilla essence
175g caster sugar
2 egg whites
one eighth teaspoon of cream of tartar
1tsp vanilla essence
food colouring of your choice
sprinkles (optional) I used some red nonpareils from Cake Angels

1. Preheat the oven to 180C and line a 10"x6.5" baking tray with silicone paper

2. Place the flour and sugar into a bowl, and rub in the butter until the mixture looks like breadcrumbs

3. In a jug mix together the egg and vanilla. Add to the breadcrumb mixture and stir with a knife to create a dough

4. Press the dough into your baking tray and pop into the oven for approximately 20 minutes

5. When the cookie base is out of the oven, allow to cool for a bit in the tray before transferring to a wire cooling tray

6. Once the cookie base is completely cool, it's time to cut it up to shape the biscuits

7. Cut the base horizontally and vertically to form biscuit squares, then cut each square diagonally to form mini triangles

8. Now we can make the frosting, place the caster sugar, egg whites, water, cream of tartar and vanilla into a bowl and use an electric whisk to beat the mixture until frothy

9. Whisk the frosting for a further 5 minutes until it is thick and glossy

10. Add your chosen food colouring and whisk the frosting for another 4 minutes until the colour is evenly distributed and you are happy with the frosting's consistency

11. Fill a piping bag with a number 18 star tip and the frosting

12. Starting at the tip of each biscuit, pipe backwards and forwards until the whole biscuit is covered