Substituting for cocoa. question?

Hey everyone!
This is my fave choco muffin recipe.

50g cornflour
3 level tbsp cocoa
100g dark soft brown sugar
225ml cold water
75g unsalted butter, cubed
125g dark chocolate, broken small
75ml sunflower oil (I just used the cooking oil in the pantry and it was fine)
2 tsp vanilla extract
2 large eggs
125g caster sugar
125g plain flour
2½ tsp baking powder

First make the custard:
Put the cornflour, cocoa, brown sugar and water into a saucepan and whisk together over a medium heat until boiling, very thick and smooth. Remove from the heat, beat in the butter and chocolate until melted and absorbed, then add the oil, vanilla and one of the eggs, and beat again until combined. Add the remaining egg and the caster sugar, and beat again until smooth and thick.

Measure the flour and baking powder into another bowl, stir together, then sift directly on to the custard and beat through until combined. Spoon into a dozen paper muffin cases sitting in the pockets of a muffin tray; heat the oven to 180C and bake for 25 minutes.

.And I was wondering, I'd like to try a white chocolate version. I can use white buttons instead of chocolate buttons to melt for the custard part. but what can I use instead of the cocoa!(for the white look rather than the chocolate look too)

thanks!

Just add the same amount of flour or custard powder. I make a chocolate cake which becomes a vanilla cake by sustituting the cocoa for extra flour.

awesome thankyou! was wondering if just flour would work but wanted to check with the experts before giving it a crack and wasting ingredients if they didn't work!thankyou muchly!

is there such a thing as vanilla powder, available here!

I've looked at importing it as it is available in vanilla producing countries - but Ihad the feeling that no-one here would know what it was. You are the first person I've seen mention it. It's hard enough convincing some NZers that real vanilla extract is different ( and vastly superior) to the rubbish in stores labelled ' natural' - the 'natural' usually meaning it is flavoured with vanillinextracted from woodpulp, which is nothing likethe real thing. Some even add afew vanilla seeds sometimes to round - off the con.

oooh neat willyow, i'm sure there'd be a wee niche for it. mine was just a logical kind of jump. there's powder chocolate, so rather than replace a powdered flavour, with unflavoured flour, maybe i could substitute one type of powdered flavour for another. then i googled "vanilla powder" :)maan that'd make my muffins AWESOME.i saw vanilla bean paste in the stupidmarket the other day, wondered if that might be enough to compensate for the extra unflavoured powder (flour)