In a small saucepan, whisk water and sugar. Bring to a boil, whisking frequently until sugar dissolves. Reduce heat to low, add the peppermint extract and simmer for 15-20 minutes until syrupy and bubbly, stirring occasionally.

In a small saucepan, heat milk over medium-high heat. Add chocolate, whisking to melt.

In a large mug, add espresso, then 2 teaspoon of the peppermint simple syrup. Stir to combine. Top with hot milk and chocolate. Add whipped cream and sprinkle with cinnamon if desired.