Preheat your oven to 170C Fan / 190C. Prepare a large baking tray with non-stick baking paper.

Cream together your softened butter and sugar until light and fluffy. (I use an electric hand mixer)

Gradually add your beaten egg and vanilla extract and mix to combine.

Add in your flour and xanthan gum and mix until combined and a dough is formed.

Lightly flour a surface (I lightly flour some non stick baking paper) and roll out your dough to just over half a cm thick. Cut out your shapes with whatever cookie cutters you have!

Bake in the oven for 8-10 minutes until the edges are very, very slightly going golden.

Leave on the tray briefly and then remove to fully cool on a cooling rack.

In a stand mixer, add your royal icing sugar and water into the bowl. Mix on a slow speed for 5 minutes, then a high speed for about 8 minutes. You could do it with an electric hand mixer or by hand in a large bowl - making this by hand would of course take longer.

Split your icing into bowls - you'll need the same amount of bowls as the amount of different colours you intend to use. If you're just doing white and red, you'll need two bowls, with half the icing in each. More colours = more bowls, dividing the icing between them as necessary. For example: I only intended to use a little black icing on my cookies, so I only put a small amount of icing in that bowl.

Mix your chosen food colouring gels into each icing bowl. Make sure you mix your colour in thoroughly so it's evenly throughout the batch until you achieve your desired colour.

Now your icing is coloured, grab more bowls and spoon a third of each icing colour into fresh bowls.

To the bowls with the larger amount of icing, add around 1 tsp of cold water (less if you only have a small amount in a bowl) and mix thoroughly until you have a slightly runnier mixture. We'll call that bowl your 'flood icing'.

For the bowls containing the flood icing, spoon into individual piping bags and seal them at the top using an elastic band or a peg so that they don't dry out - place them to one side as we won't need those for a while.

With the bowls containing the smaller amount of icing, spoon those into individual piping bags too - we'll call these your 'outline icing'. Make sure you don't confuse these with the flood icing piping bags of the same colour. It's easily done!

Snip off the end of your outline icing bags so it leaves a hole that's roughly 1-2mm. For the next part, I've added a video above the recipe card showing you the technique - definitely watch this first if you've never done this before!

Carefully pipe a line all around the edge of your Christmas cookies in your colour of choice. TIP: Don't use it like a pen! Start with the piping bag touching the cookie and as soon as the first little blob of icing makes contact and sticks, then raise your piping bag slightly above the cookie for the rest of the outline. Continue that line, allowing it to constantly fall into place as you move the piping bag around the edge of the cookie. Repeat for all of your outlined cookies and allow to set for 5 minutes.

Grab your flood icing piping bag (using the same colours to match the outlines), snip off the end (leaving a slightly bigger hole than your outline icing bags) and pipe a generous amount right into the middle, leaving a 1/2cm gap from your piped outline.

Using a cocktail stick, now swirl/spread the icing so that it meets the line, but be careful not to go over it. Repeat using all the colours you've prepared until all of your Christmas cookies are flooded. If adding sprinkles to the top of some of the cookies like I did, add these now.

You can either allow the flood icing to air dry for an hour in a warm place or place them onto a baking tray and pop them back in the oven at 55C for 20 minutes.

Once the icing is really nice and set, grab your outline piping bags once again. Use these to pipe detail onto the flooded cookies in contrasting colours. For the snowman/wreath, I piped a red outline for the scarf/bow, then used a teeny bit of my flood icing to flood the shape. The same goes for the snowman's nose. For other cookies, I simply piped dots on the trees for baubles and a pattern on my gingerbread men's jumpers.

Allow them to set for 20 minutes and enjoy!