Preparation Preheat oven to 350°F. Butter four 1/2-cup muffin cups. Sprinkle with sugar to coat. Combine cream, butter, cocoa, orange peel and espresso powder in heavy small saucepan. Bring to simmer, whisking until blended. Remove from heat. Add chocolate; stir until melted. Cool to lukewarm, about 10 minutes. Using electric mixer, beat egg and sugar in medium bowl until pale yellow and slowly dissolving ribbon forms when beaters are lifted, about 4 minutes. Fold in walnuts and vanilla. Gently fold in chocolate mixture. Divide batter among prepared muffin cups. Bake cakes until puffed and tester inserted into center comes out clean, about 18 minutes. Cool in pan on rack 10 minutes (cake centers may sink.) Turn cakes out onto rack. (Can be made 1 day ahead. Cool completely. Cover and store at room temperature. Rewarm uncovered in 350°F. oven about 10 minutes.) Arrange warm cakes bottom side up on plates. Surround with mango. Sprinkle with crystallized ginger. Top cakes with whipped cream, if desired.
Preparation Preheat oven to 350°F. Butter four 1/2-cup muffin cups. Sprinkle with sugar to coat. Combine cream, butter, cocoa, orange peel and espresso powder in heavy small saucepan. Bring to simmer, whisking until blended. Remove from heat. Add chocolate; stir until melted. Cool to lukewarm, about 10 minutes. Using electric mixer, beat egg and sugar in medium bowl until pale yellow and slowly dissolving ribbon forms when beaters are lifted, about 4 minutes. Fold in walnuts and vanilla. Gently fold in chocolate mixture. Divide batter among prepared muffin cups. Bake cakes until puffed and tester inserted into center comes out clean, about 18 minutes. Cool in pan on rack 10 minutes (cake centers may sink.) Turn cakes out onto rack. (Can be made 1 day ahead. Cool completely. Cover and store at room temperature. Rewarm uncovered in 350°F. oven about 10 minutes.) Arrange warm cakes bottom side up on plates. Surround with mango. Sprinkle with crystallized ginger. Top cakes with whipped cream, if desired.