Bittersweet Chocolate Sauce

1/4 cup margarine or butter
1-1/2 squares (1-1/2 ounces) unsweetened, cut into pieces
3/4 cup sugar
1/4 cup cocoa
1/4 cup half-and-half
1/8 teaspoon salt
1 teaspoon vanilla

Heat margarine and chocolate in 1-quart saucepan over low heat, stirring constantly, until smooth.

Stir in sugar, cocoa, half-and-half and salt. Heat slowly to boiling; do not stir.

Remove from heat; stir in vanilla. Serve warm.