Combine 2 cups cake mix, milk, and oil, stirring mixture well. (Reserve remaining 2 cups cake mix for another use.) Stir in 1/3 cup crushed peppermint candies. Spoon batter into a lightly greased 8" square pan.
Combine sugar and cocoa; sprinkle over batter. Pour boiling water over batter (do not stir).
Bake, uncovered, at 350° for 35 minutes. Let stand 5 minutes before serving. Serve warm pudding cake with vanilla ice cream. Garnish, if desired.
Note: For cake mix, we used Duncan Hines. There are 4 cups cake mix in the package. Seal the unused portion in a zip-top plastic bag, and make the dessert again!