Directions

1. Preheat oven to 400°F. Rub 2 tablespoons of the butter on the inside of 4 ovenproof ramekins. Sprinkle 1 tablespoon of the sugar to coat the inside of ramekins. Place ramekins on a baking sheet. Set aside.
2. In a double boiler combine 1/2 cup of the butter plus chocolate. Heat gently, stirring to melt butter and chocolate completely. Add vanilla, Grand Marnier and orange zest. Remove from heat; let cool completely.
3. In a clean mixing bowl and using an electric mixer, whisk egg yolks and 1/3 cup of the sugar until mixture is pale yellow, thick and fluffy. Fold yolk mixture into chocolate mixture.
4. In a clean mixing bowl whisk egg whites, remaining 1 tablespoon sugar and cream of tartar until stiff peaks form. Fold egg whites into chocolate mixture. Spoon batter evenly into ramekins.
5. Place baking sheet in oven. Bake 10 minutes or until the outside edges of the cakes are set. Remove from oven immediately. Serve cakes in ramekins, or run a knife around the edge of each cake and invert onto a plate, carefully removing the ramekin. Serve with ice cream (if desired), and sprinkle with orange zest and powdered sugar.