Preheat your oven to 350°F (180°C).
Grease the bottom and sides of your springform pan and line it with parchment paper.
In a saucepan, melt the chopped chocolate and butter over low heat, stirring constantly until smooth. Let it cool for a few minutes.
In a mixing bowl, beat the egg yolks and sugar until light and fluffy.
Gradually add the chocolate mixture to the egg yolk mixture, stirring until well combined.
In a separate bowl, beat the egg whites until stiff peaks form.
Gently fold the egg whites into the chocolate mixture, using a spatula until no white streaks remain.
Pour the batter into the prepared pan and smooth the top with the spatula.
Bake for 35 minutes or until a toothpick inserted in the center comes out clean.
Let the cake cool in the pan for 10 minutes before removing it and placing it on a wire rack.
Once cooled, dust the top with powdered sugar and add any desired toppings before serving.