Preheat the oven to 180°C, fan 160°C, Gas Mark 4.
Line a 20cm springform cake tin with butter and cocoa powder.
Melt the chocolate in a bowl set over a pan of boiling water. Set aside to cool slightly.
Beat the eggs with the sugar, yogurt and oil. Stir in the melted chocolate.
Sift the flour, baking powder, ground almonds and cocoa powder together.
Fold the dry ingredients into the egg mix, and pour into the prepared mould.
Bake in the oven for 30-45 minutes, or until a wooden skewer comes out clean from the centre of the cake.
*All information included in this recipe has been provided by Onken.