2squares unsweetened chocolate(4 small squares are equivalent to 1 square as noted on box.)
Preheat oven to 325 degrees and butter and flour an 8 inch baking pan.
Melt butter and chocolate squares in a medium saucepan. When melted remove from heat and stir in the sugar. Add the eggs and vanilla and beat well with a whisk. Stir in the flour and salt. Pour into prepared baking pan and bake for 30 - 35 minutes.