Pre-heat your oven to 200 degrees and then start off by whisking the butter and sugar together until it;s pale and creamy. make sure your butter is at room temperature so it blends easily. Crack in the egg and mix it through. Gradually add the flour by piping in a bit at a time, until it is all mixed in.
The mixture should then come together and look like dough. if it looks too dry, add a dash of milk until it’s the right consistency. If th emixture feels too sticky, just add a touch more flour.
With clean hands, break up the chocolate into big and small chunks and add to the mixture. Grab the dough from underneath and spread the chunks through thoroughly. Shape the mixture into ten balls using your hands and put on a baking tray covered in greaseproof paper.
Bake these for 10-12 minutes but no longer! They will look like they need longer, but don’t do it!
Leave them to cool on a baking tray or cooling rack to cool for 25 minutes. They should be gooey on the inside and hard on the outside- so, so good!