Melt margarine and chocolate in a large saucepan, being careful not to burn.

Remove from heat, add sugar, gradually stiring until melted. Add eggs, stirring in one at a time. Add vanilla.

Stir in flour and salt, a little at a time. Blend well.

Pour into a well greased 8 inch glass pan. Bake at 350 degrees for 25 minutes. Cool well, cut into delicious squares.