Line a 15 x 10 x 1-inch baking sheet with parchment paper. Set aside. In a large mixing bowl, add marshmallows, chocolate morsels, unsweetened chocolate, and vanilla extract. Set aside. In a large saucepan, combine sugar, milk and butter. Over medium high heat, bring mixture to a boil while stirring constantly. Once boiling, boil for a full two minutes. Pour hot mixture over marshmallow and chocolate and beat with whisk attachment until melted and smooth (may take several minutes). Pour into prepared baking sheet and refrigerate for about 3 hours (or overnight). Remove from refrigerator and cut into 4 large rectangles. Wrap in parchment paper and store in airtight container until ready to use. When ready to use, cut into bite sized pieces and enjoy.