About this recipe:Homemade brownies tend, dare I say it, to be little more than raw cakes - with those funny floating flakes of crust on the top and a ring of dubiously chewy batter around the edge. In restaurants (and even supermarkets) they're joyously dense and solid; as nature intended them, if you like. That is how a brownie should be, and that is what this recipe will make.
Preheat the oven to 180 C / Gas 4 and grease a tin of approximately 20x25cm. Line the bottom with parchment, then grease the paper.
Place 200g plain chocolate, 50g of the milk chocolate and the margarine into a heatproof bowl over a saucepan with gently simmering water. Stir occasionally until smooth and fully melted. Allow to cool.
Add 2 tablespoons of hot water to the coffee in a small pot or ramekin and place to the side.
Break the egg whites into a large mixing bowl and whisk until stiff. Add the sugar and whisk again.
Place the yolks in a separate bowl and beat. Mix in the coffee mixture, vanilla and cinnamon, then carefully add to the whites and fold in.
Gradually, add the flour and cocoa - folding in so as to avoid deflation.
Chop the remaining milk and white chocolate, mix, then fold around three quarters into the main mixture.
Scrape the mixture into the greased baking dish then scatter the remaining chocolate on top. Flatten surface with a spatula.
Place in the oven for 35-40 minutes, covering with tin foil if necessary to avoid burning.
Remove from oven and leave until cool, then transfer dish to the fridge and leave for as long as humanly possible. After about 4 hours they'll cut cleanly with a fine knife, but cut sooner if you're prepared to put up with some crumbling.