There are some recipes which are simply better without flour. It is one of them.
100g/3½oz walnuts, roughly chopped
(1) Preheat the oven to 180C/350F/gas 4. Line a 28cm (11in) brownie tin with baking paper.
(2) Suspend a bowl over a pan of simmering water (making sure the water doesn’t touch the bottom) and melt the chocolate and butter, stirring a couple of times until the chocolate is just melted.
(3) In a separate mixing bowl, use an electric whisk to beat the eggs, sugar and 1 tsp of salt until very light and fluffy and doubled in volume. Stir in the melted chocolate mixture, and when it is incorporated stir in the walnuts. Pour into the tin and place in the oven for 20-25 minutes at 180C, until the surface is firm but gives a little when you touch it. Leave to cool in the tin before cutting into squares.