Preheat oven to 350° and lightly butter springform pan and dust with extra sugar. Be sure to tap out excess.
Combine chocolate, oil and butter in heat proof bowl and place over simmering water. Water should not be touching bowl. Stir until chocolae is melted and incorporated. Remove from heat.
In a bowl whisk the 4 yolks plus 2 whole eggs, cocoa powder, vanilla and salt. Temper the chocolate with the egg mixture then whisk all together, until smooth.
Use an electric mixer to beat the egg whites until frothy then gradually start adding 1/2 cup of sugar. Continue beat until you have firm peaks. Fold egg whites into chocolate mix, until just incorporated. You may want to do this in two steps.
Pour batter into prepared pan and smooth top level. Sprinkle with remaining 2 Tbs. sugar.
I like to put pan on a baking sheet and then bake for 35-45 minutes. The top of the cake should be cracking and the edges pulling away, slightly.
Cool completely on a wire rack. Dont worry the cake is suppose to fall inthe center.
Use an electric mixer, start beating the mascarpone then add the heavy cream and sugar. Beat until soft, cloud-like, peaks form.
Once cake is completely cooled, loosen sides of springform and remove from cake.
Mound whipped cream in center of cake and garnish with chocolate shavings or fresh fruit and mint leaves. Enjoy!