Tip the yogurt onto a piece of cheesecloth, muslin or a milk bag, place in a bowl and chill for at least two hours or overnight to strain. Whisk the strained yogurt with xylitol and cacao and place in the fridge.

Heat the oven to 200C/180C fan/gas 4. Soak a sheet of parchment paper with water, then crumple it and wring it out. Use it to line a 22cm springform pan. In a clean, dry bowl, whisk the egg whites to stiff peaks using an electric whisk.

In a medium bowl, combine the egg yolks, coconut oil and vanilla extract. Add the almond flour, xylitol, cacao powder, baking soda, milk and apple cider vinegar. Gently fold in the whites and baking powder into the mixture. Pour the batter into the prepared pan.

Bake at 180C/160C fan/gas 4 for 15 mins, then reduce the temperature to 160C/140C fan/gas 3 and bake for a further 15 mins. The cake is ready when a skewer inserted in the middle comes out a bit sticky but without batter clinging to it. Keep an eye on the cake during the last few minutes because it can brown quickly. Remove from the oven and leave to cool completely before releasing it from the springform pan and placing on a serving platter. Spread the icing over the top of the cooled cake. Dust with more cacao powder, if you like.