Fromage blanc is a soft, fresh cream cheese that is similar in consistency to sour cream.
Make the tuiles: Preheat oven to 350 degrees. Put egg white and sugar into the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-high speed 30 seconds. Add flour, cocoa powder, and salt; mix 30 seconds. Add butter and cream; mix 30 seconds.
Cut out a 2-by-3 1/4-inch teardrop template from a plastic lid. Using template, thinly spread batter with an offset spatula into eight teardrops on a baking sheet lined with a nonstick baking mat. Bake 3 minutes. Working quickly and using a spatula, drape tuiles over rolling pins; let cool, then transfer to wire racks. Repeat with remaining batter. Brush concave side of each tuile with chocolate; let set on racks. Tuiles can be stored in airtight containers up to 3 days.
Make the mousse: Sprinkle gelatin over 1/4 cup cold water in a small saucepan. Let stand 1 minute. Heat over low heat, stirring, until dissolved, about 1 minute. Transfer to a bowl; let cool completely.
Prepare an ice-water bath; set aside. Bring 1/2 cup cream, the cardamom, and orange zest to a boil in a small saucepan over medium-high heat. Remove from heat, and let steep 10 minutes. Set pan in ice-water bath, and let cool completely.
Transfer cream mixture to the bowl of an electric mixer fitted with the whisk attachment. Add remaining 1/2 cup cream. Beat on medium speed until medium-stiff peaks form. Add fromage blanc, and beat until stiff peaks form. Add gelatin mixture and orange-flower water, and beat until just combined. Transfer to a medium bowl; set aside.
Put egg whites, sugar, and cream of tartar into the clean bowl of an electric mixer fitted with the whisk attachment. Beat on medium-high speed until stiff peaks form. Gently fold egg white mixture into fromage blanc mixture. Refrigerate until firm, about 4 hours. To serve, spoon about 1 teaspoon mousse onto chocolate-covered side of each tuile. Dust with confectioners' sugar.