Preheat oven to 350 degrees F.
Melt the butter and chocolate together in a medium pan over very low heat. Stir together and remove from the heat. Add sugar, eggs and vanilla. Mix well. Stir in the flour and salt. Add nuts. Spread the mixture into a buttered 8-inch square pan. Bake until set, about 40 minutes. Cool before cutting.
Recipe courtesy Gale Gand