Preheat the oven to 190/375/gas 5. Line a muffin tray with paper cases, or if using a cupcake tray & liners, get about one and a half trays ready.
Sieve all the dry ingredients together in a large bowl, adding the chunks of chocolate in last.
Measure the wet mix out in a jug.
Pour the wet into the dry and stir briefly, just enough to get rid of any dry patches of mix. Over stirring will create dense, rubbery muffins.
Scoop into the paper cases and bake for 20-25 minutes, or until the top springs back when gently pressed or a skewer comes out clean. If you are using a cupcake tray & cases, they will need less time to cook.
Pop onto a cooling rack until cool enough to munch :)