unsweetened chocolate squares
Heat milk and chocolate together in heavy saucepan over low heat until chocolate is melted.
Add sugar, salt and corn syrup.
Cook, stirring until boiling starts.
Cover and boil 3 minutes to wash down sugar crystals from pan sides.
Cook without stirring until thermometer reaches 232 degrees.
Remove from heat and cool without stirring to lukewarm.
Add vanilla and beat until fudge thickens and looses its gloss.
Cut each marshmallow into 8 pieces and stir into fudge.
Cut into squares when firm.