Thoroughly wash the orange, scald with boiling water, and dry. Then cut off a slice, and grate the peel from the remaining part (use the rest of the orange for another meal).

In a saucepan, place milk, a little water (about ¼ cup), cocoa, sweetener, and broken chocolate. Heat over medium heat until the ingredients combine and dissolve (a few minutes). Stir occasionally (preferably with a hand whisk). At the end, add the grated orange peel and mix thoroughly.

Pour the chocolate into a glass and garnish with a slice of orange.