Ricotta and Coffee Mousse (Spuma di Ricotta al Caffè)

Purée ricotta in a blender until smooth. Transfer to a large bowl; set aside.

Whip together heavy cream and sugar in a large bowl until soft peaks form. Set aside.

Bring 1⁄4 cup water to a boil in a small saucepan; remove from heat. Whisk 2 tbsp. of the water with espresso in a small bowl. Whisk remaining water with gelatin in another small bowl until dissolved.

Stir espresso mixture into ricotta, then gelatin mixture; fold in cream in 3 stages. Chill mixture for 1 hour, then transfer to a pastry bag fitted with a star tip. Pipe mixture into 6 sundae glasses; refrigerate until set, about 1 hour. Garnish with shaved chocolate.