Line 8x8 or 9x9 pan with foil. Combine semisweet and milk chocolate chips (3 cups), sweetened condensed milk, vanilla and butter in heavy saucepan over low heat. Melt chocolate, stirring constantly, until mixture is smooth. Remove from heat and fold in mashmallows, nuts, optional mini chips. Pour mixture into pan. Do not smooth top of fudge. Refrigerate until firm. Lift fudge from pan. peel back foil and cut into pieces. Store in airtight container, refrigerated, up to 2 weeks. Bring to room temperature before serving. Makes 2 3/4 pounds.
|