Steps

1. Preheat oven to 375 °F. Butter and flour a 9 x 13 x 2 inch baking pan.
2. Melt chocolate and butter together, stirring often. Remove from heat and cool.
3. Combine the eggs, vanilla extract, salt, and sugar in a mixing bowl and beat for 8 to 10 minutes, until light in colour, fluffy, and the sugar has dissolved.
4. Gently stir in the chocolate and butter mixture, then fold in the flour just until well blended. Stir in the walnuts.
5. Spread in the prepared baking pan and bake about 25 minutes, until the edges are set but the center is still slightly moist.
6. Cool in the pan a few hours, then cut into squares.