Put the toffee sauce ingredients 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, 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.
