In a large mixing bowl, combine milk powder, confectioner's sugar, cocoa powder, and creamer. Stir till thoroughly combined. Store cocoa mixture in an airtight container. Makes about 15 cups mix, or enough for about 45 servings.
For 1 serving, place 1/3 cup cocoa mixture in a coffee cup or mug, and add 3/4 cup boiling water. Stir to dissolve. Top with dollop of whipped cream or a few marshmallows, if desired.