Step 1

Grease 4 regular sized mugs or 4 small ramekins and preheat your oven to 350F / 180C .

Step 2

Put the flour, sugar, cocoa, baking powder and a pinch of salt in a large mixing bowl and mix until combined.

Step 3

Whisk together the eggs, melted butter, coffee, vanilla and milk, then pour into the dry ingredients and mix until smooth. Stir in the chocolate chunks.

Step 4

Divide the batter into 4 containers, filling about ⅔ of the way.

Step 5

To make the sauce: In a small bowl mix together the boiling water, sugar and cocoa powder until the sugar is dissolved.

Step 6

Pour the sauce over the chocolate batter. Divide it between the 4 mugs.

Step 7

Bake on the middle shelf of the oven for 20-25 minutes until the surface looks risen and crisp. Dust with icing sugar, and top with ice cream if you like and serve straight away – as you scoop to the bottom of your mug you should find a gorgeous chocolate sauce underneath!