1 tsp vanilla essence chocolate sprinkles, to serve
For the chocolate ganache
100g dark chocolate, broken into pieces
5 tbsp double cream
Grease a 22cm silicone microwaveable cake pan with a little oil and place a circle of baking parchment in the bottom.
Mix the sugar, flour, cocoa and baking powder in a bowl. In a jug, whisk the oil, eggs, vanilla and 100ml hot water until combined.
Add the liquid ingredients to the dry ingredients and mix thoroughly until you have a lump-free batter. Pour the mixture into the cake pan and gently tap to pop any air bubbles. Cover with cling film.
Microwave on Full power (800 watts) for 7 mins. Remove and check if the cake is cooked by poking a skewer into the middle: if it comes out clean, the cake is ready. Allow the cake to stand for 5 mins, then remove the cling film and turn out onto a cooling rack.
For the ganache, melt the chocolate on Half power (600 watts) for approximately 2 mins, stirring every 30 secs until melted. Add the cream and mix thoroughly until smooth and glossy.
Once the cake is cool, spread over the ganache and scatter with the sprinkles. The cake will keep for up to 3 days in an airtight container.