WAFER Mixture: Line 8-inch pan with 9 wafers. Place margarine and brown sugar in large saucepan. Add milk and vanilla; stir. Bring to boil on medium-high heat; cook 5 min. Remove from heat.
ADD graham crumbs and peanut butter; mix well. Pour over wafers in pan; cover with remaining wafers. Refrigerate 1 hour or until firm.
ICING: BEAT margarine and peanut butter in large bowl until well blended. Add icing sugar, milk and vanilla; mix well. Spread over dessert.