Preheat the oven to 160° C.

In a large bowl, beat the butter and sugar together with an electric beater or wooden spoon till the mixture is pale and fluffy; this takes up to 10 minutes. Next, with the mixer still on, gradually add in the beaten egg. In a separate bowl, sieve together the flour, bread soda, salt and cocoa powder, then gently fold this into the wet mixture in stages. Finally, fold in the chocolate chips.

I use dark chocolate, but to make these more kiddie-friendly, you could use milk chocolate. Chill the mix for an hour in the fridge. Line baking sheets with parchment, divide the dough into balls about an inch across, leaving plenty of space between them (at least four inches) and bake for 12-15 minutes. Don’t worry if they seem a little soft as they do crisp up – and anyway, they’re nicer if a little chewy.