Put the lavender buds into a teapot and pour over 440ml boiling water. Leave to infuse for 1 hour. Strain off and heat in a pan to near boiling.
Break the chocolate into a bowl then pour the hot lavender water over it. Leave for a few minutes to melt then stir until smooth.
Sift together the flours, bicarb of soda, cocoa and salt.
Cream the butter and sugar until light and fluffy.
Beat in the eggs alternately with the flour mixture.
Stir in the chocolate ganache until thoroughly mixed.
Spoon mixture into a lined 9″ (23cm) square deep cake tin or silicone mould and bake for about 40 mins at 180℃ (350℉, Gas 4) or until an inserted skewer comes out more or less clean. Leave to cool a little then turn out onto a wire rack to cool completely.
Chocolate Yoghurt Icing
Melt the chocolate, butter and golden syrup in a large pan. Leave to cool slightly.
Stir in the yogurt until thoroughly combined.
Spread over the cooled cake.Scatter a few dried lavender buds over the top if liked.