Nigel Slater's Best Brownies. Heaven in a tin. The fudgy moist centre is the aim. 

300g caster sugar

250g butter

250g chocolate (70% cocoa solids)

3 large eggs plus 1 extra yolk

50g gluten free flour (60g plain wheat flour)

60g cocoa powder

½ tsp baking powder

Preheat oven to 180ºC and line a baking tin with greaseproof paper. 

Mix the sugar and butter into a fluffy pale cloud. Set aside 50g of the chocolate (chop it up into gravel-sized pieces) and melt the rest - 20 seconds at time in the microwave, stirring after each blast. Meanwhile sift together the flour, cocoa, and baking powder with a pinch of salt.

Mix the beaten eggs into the sugar and butter fluff, a quarter at a time. Beat fast in between additions. Add the melted chocolate and the broken up chocolate (i used white chocolate in this version) then fold in the flour/cocoa and baking powder mixture as gently as possible. 

Put the mixture into the cake tin and put it into the oven for 25 minutes. The surface should have crusted over, but with a wobble underneath. Check with a skewer - if too much mixture clings then put it back for 3 more minutes, but no longer.