Place the butter in a large mug and microwave it for 20 to 30 seconds until melted.
Add the egg* and whisk it in with a fork.
Stir in the milk, vanilla, and sugar.
Add the flour, baking powder and salt. Mix the batter with a fork until smooth.
Cover with cling film and microwave for 1 minute and 20 seconds.
Empty the custard into a jar and heat until hot.
Put the cocoa powder and sugar into a hug.
Pour half of the custard onto the cocoa powder and mix.
Pour plain custard over Sponge then drizzle the chocolate custard over the Sponge. Lastly sprinkle crushed honeycomb on top of the Sponge.
2 tablespoons butter
1 large egg
2 tablespoons milk
1 teaspoon pure vanilla extract
3 1/2 tablespoons caster sugar
6 tablespoons flour
1/4 teaspoon baking powder
Tiny pinch of salt
Tin of custard
Tablespoon Cocoa powder
2 teaspoons of caster sugar