Preheat your oven to 180C (160C Fan) and prepare a 2lb loaf tin with baking/parchment paper.

Cream together your softened butter and sugar using an electric hand whisk. Do so until lighter in colour and fluffier in texture.

Gradually add your eggs (I whisk briefly in between each addition), mix in alongside your orange extract.

Sift your gluten free flour, cocoa, baking powder and xanthan gum and then mix with your electric hand whisk until combined.

Spoon your mixture into your prepared loaf tin and place in the preheated oven for 50 minutes.

After 50 minutes, remove from the oven (check with a skewer it's fully cooked) and leave to cool in the tin. Remove from the tin and put to one side on a cooling rack whilst you make the buttercream.

Whilst your cake cools you can make the chocolate orange buttercream. Place your butter in a stand mixer (or electric hand whisk if you don't have a stand mixer), mix on its own on a high speed for about 5 minutes. The butter should change from a more yellow colour to being a lot more pale.

Melt your dark chocolate (I do this is the microwave), put to one side to cool whilst making the rest of the buttercream.

Add your icing sugar gradually to the butter (I do this in two stages), I mix each addition of icing sugar for around 3-5 minutes before adding the second half.

Now add in your melted dark chocolate and orange extract and mix briefly to combine. It should be the right consistency at this point. If you think it's too thick you can add a tsp of milk. If too thin you can add more icing sugar. I've never needed to do either though.

Spread your icing all over the top of your cake and then place chocolate buttons and orange zest on top to finish.

Enjoy!