Preheat the oven (fan oven at 180°C).
Mix the dry ingredients in a bowl. Heat the butter in a saucepan until melted and remove from the heat. Mix the lemon juice, melted butter, milk and the melted coconut oil in a separate bowl and add to the dry ingredients. Mix well together to form a dough.
Pour the batter into a silicone muffin pan.
Bake for 20 minutes. Leave to cool completely and then remove from the mold. Melt the chocolate, pour over the muffins and top off with Matcha powder!