Mini Marshmallows Melt butterscotch chips and 1 tablespoon of oil in top of double boiler over hot, not boiling water. Stir in walnuts. Pour into pan. Arrange one layer of mini-marshmallows on top. Melt chocolate chips and 1 tablespoon of oil in top of double boiler over hot, not boiling water. Pour over marshmallows. Chill. Use a hammer and chisel to cut.