With the rack in the middle position, preheat the oven to 350°F (180°C). Butter an 8-inch (20 cm) springform pan and line the bottom with parchment paper.
In a bowl, combine the dry ingredients. Stir in the water, oil and vinegar with a whisk until smooth. Spoon into the prepared pan.
Bake for 10 to 12 minutes or until a toothpick inserted into the centre of the cake comes out clean. Let cool on a wire rack. Do not unmould.
In a bowl placed over a pot of simmering water or in the microwave oven, melt the chocolate. Let cool slightly.
In a small bowl, sprinkle the gelatin over the water and let bloom for 5 minutes.
In a small saucepan over medium heat, heat cup (60 ml) of the cream with the sugar until the sugar has dissolved. Remove from the heat and stir in the gelatin until completely dissolved. Add the cream mixture to the melted chocolate and stir to combine.
In another bowl, whip the remaining cream (1 3/4 cups / 430 ml) with an electric mixer until stiff peaks form. Combine one-quarter of the whipped cream with the chocolate mixture. With a spatula, gently fold in the remaining cream. Spoon onto the cake in an even layer. Refrigerate for 4 hours or freeze.
Unmould the cake and place on a serving platter. If frozen, leave the cake at room temperature for 1 hour.
Place the chocolate in a bowl. Set aside.
In the microwave oven or in a small saucepan, bring the cream to a boil. Add to the chocolate and let melt for
1 minute. With a spatula, stir the ganache until smooth. Pour over the cake, letting it run over the sides.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.