Preheat the oven to 150 °C. Line a 9-inch spring-form cake tin with greaseproof paper.
Melt the chocolate in a metal or glass bowl placed over a pot of barely simmering water, stirring constantly. Once melted, remove the bowl from the heat and let cool slightly.
Whip the egg whites with 50g sugar until the whites hold a soft peak. Set aside.
In another bowl, whip the egg yolks with the remaining 50g of sugar and the vanilla until doubled in volume. (It should take about 4-6minutes)
Fold the melted chocolate into the whipped yolks, and then fold the whites into the mixture in 2 stages. Spread the batter gently into the prepared cake tin.
Bake the torta for 35 minutes. As soon as you remove the cake from the oven it will begin to fall, but it is supposed to.