Layer cocoa powder, powdered milk, brown sugar, salt, ground cinnamon, and Mexican chocolate. Add a few cinnamon sticks to top of jar.
This mix will fill a 1-quart jar (12 servings), but if your containers are different sizes, just keep the ratio of ingredients constant. On the back of the tag, write: "Mix contents in a large bowl. For each serving, place 1/3 cup cocoa mix in a mug and stir in 1 cup boiling water. Store remaining mix in airtight container."