Purée 1 15-ounce container whole milk ricotta cheese, 1 Tablespoon cocoa powder and 1/2 cup strong brewed coffee in a blender until smooth. Transfer to a large bowl; set aside.
In a separate bowl, using an electric mixer, beat the 1 cup whipping cream until thick. Add the 4 Tablespoons powdered sugar and continue to beat until the cream holds stiff peaks.
Fold in cream into the ricotta mixture in 3 stages. Spoon the mousse into serving bowls and refrigerate for 1 hour.
Garnish with chocolate shavings and mint and serve.
Notes
How to make ahead & store
This mousse will keep in the refrigerator, tightly covered, for up to four days.