Heat oven to 170°C/150°Fan/gas 3. Grease and line a 20cm square tin with baking paper.
Combine the flaxseed with 6 tbsp water and leave to stand for 5 minutes
In a saucepan melt 120g chocolate, the coffee granules and butter with 60 ml water on a low heat. Allow to cool slightly
Put the flour, almonds, cocoa powder, baking powder and salt in a bowl and stir to remove any lumps. Using a hand whisk, mix the sugar into the melted chocolate mixture, and beat until smooth and glossy. Make sure all the sugar is dissolved. Stir in the flaxseed mixture, vanilla extract and the remaining chocolate, then the flour mixture. Spoon into the tin.
Bake for 35-45 minutes until you can insert a skewer into the middle and it comes out clean. Leave in the tin until completely cool,, then cut into squares