1. Line tray or cookie sheet with wax paper.
2. Combine butter and milk in large microwave-safe bowl. Microwave at HIGH (100%) 1 minute or until butter is melted when stirred; stir in sugar and cocoa until well blended. Microwave at HIGH 1-1/2 minutes; stir. Microwave at HIGH an additional 1-1/2 to 3 minutes or until sugar is completely dissolved and mixture is hot and bubbly on surface; carefully stir in salt, vanilla and oats.
3. Drop by tablespoons onto prepared tray; flatten slightly. Let stand until firm. If necessary, cover and refrigerate until firm. Top with FOOLPROOF BUTTERSCOTCH FUDGE CUT-OUTS, if desired. Makes about 36 cookies.
FOOLPROOF BUTTERSCOTCH FUDGE CUT-OUTS: Line 15-1/2x10-1/2x1-inch jelly-roll pan with foil. Combine 3 cups (almost two 11-oz. pkgs.) HERSHEY'S Butterscotch Chips and 1 can (14 oz.) sweetened condensed milk (not evaporated milk) in large microwave-safe bowl.
Microwave at HIGH (100%) 1 minute; stir. Continue heating 15 seconds at a time, just until chips are melted and mixture is smooth when stirred. Immediately spread evenly into prepared pan. Cover; refrigerate until firm. Use foil to lift fudge out of pan; place on cutting board. Peel off foil. With small cookie cutters, cut into favorite shapes. About 2 pounds fudge.