1. Preheat the oven to 180C and grease one 7-inch round cake tin with butter.
2. Melt butter in a mixing bowl and sift in gluten free flour and cocoa powder.
3. Prepare the egg replacer by mixing it with the water and allowing it to sit for a minute.
4. Pour in the almond milk, vanilla extract, olive oil, egg replacer into the bowl and combine.
5. Put the batter into the cake tin and place into the oven to bake for around 30-35 minutes. Move to a cooling rack and allow to cool completely before frosting.
6. Prepare the chocolate ganache frosting by mixing the butter, icing sugar and cocoa powder until smooth.
7. Frost onto the cake and finish with pieces of the vegan honeycomb chocolate bar, or toppings of your choice. Cut into slices and enjoy!