In a small saucepan, combine the cocoa and water, whisking until smooth. Add the sugar and mint leaves, stirring until combined. Place saucepan on medium heat. Bring mixture to boil, stirring constantly to melt sugar. As soon as the mixture boils, reduce heat and simmer for 5 minutes, or until mixture is thickened and glossy. Remove from heat and let cool. Store in refrigerator.
“Plant a little mint, Madame, then step out of the way so you don't get hurt!”