Put the toffee sauce ingredients (butter, light brown soft sugar, double cream) into a large heatproof mug and cook on high for 30 seconds
Stir, then cook for another 30 seconds-1 minute until you get a bubbling toffee sauce
Carefully pour half of the sauce into a separate dish
Add the dates to the remaining sauce in the mug, along with the rest of the sponge ingredients (light brown soft sugar, self-raising flour, neutral oil, egg), and stir well
Cook on high for 2 mins, until the sponge is well risen, and springs back when pressed
Pour over the remaining toffee sauce, and a drizzle of cream if you like
