Preheat oven to 375 degrees F. Grease a 9 x 13 pan.

Melt chocolate and butter in a saucepan over low heat; set aside. In a mixer, beat eggs, sugar and vanilla at high speed for 10 minutes. Blend in chocolate, flour and salt until just mixed.

Stir in the nuts. Pour into prepared pan.

Bake for 35-40 minutes. (Don't overbake.) Cool and frost if desired.