Pre-heat your oven to its highest setting (temperature will be reduced when muffins go in). Prepare your muffin tray by lining with cases and set aside.
Sift together into a bowl: flour, sugar, cocoa powder, baking powder and bicarbonate of soda, and set aside.
In another bowl put all your wet ingredients: soured cream, oil, eggs, milk, vanilla and chocolate extracts, and mix well.
Sift all your dry ingredients into the bowl with the wet ingredients, when sifted add chocolate chips and fold mixture 15 times ONLY.
Spoon your mixture into your muffin cases so they are each 3/4 full and place in your oven on the middle shelf, reduce temperature to 190 C / Gas 5 and bake for 25 to 30 minutes until the tops are firm to touch.
Let the muffins sit in the tin for 1 to 2 minutes after you take them out of the oven, place them on a cooling rack for 10 minutes and then serve still warm, mmmmm!
Place a roasting tray or any oven proof container full of water on the bottom shelf of your oven when baking your muffins; it will help keep them really moist.
Hold your sieve high above bowls when sifting dry ingredients; this will make your muffins really light.
To help your chocolate chips keep their shape in the muffins, freeze them before using.
MOST IMPORTANT! Remember to only stir your mixture 15 times; this is the key to great muffins. Don't be tempted to over-stir no matter what your mixture looks like.
I like my muffin tops quite soft so while they are cooling I put them in a sealed container to 'sweat' this keeps the muffins nice and soft and really moist.