Preheat oven to 375 degrees F (190 degrees C).

Grease a 9-inch springform pan and dust with 1/2 teaspoon unsweetened cocoa powder.

Melt chopped chocolate squares and butter in a heavy saucepan over low heat, stirring until smooth.

Whisk egg yolks and vanilla extract together in a large bowl.

Gradually whisk chocolate and butter mixture into egg yolk mixture until well blended.

Beat egg whites in a separate bowl with an electric mixer on high speed until soft peaks form.

Gradually beat sugar into egg whites until sugar dissolves and egg whites hold stiff peaks.

Fold 1/3 of the egg white mixture into chocolate mixture. Gently fold in remaining egg white mixture until just blended and batter is smooth and fluffy.

Spread batter evenly into prepared springform pan.

Bake in the preheated oven until sides begin to pull away from pan and top is set in center.

Let torte cool in pan on a wire rack for 10 minutes before removing the sides of the pan.

Place chocolate chips into a microwave-safe bowl and heat in microwave on full power for 1 minute. Stir the chips and continue to heat in 15-second intervals, stirring after each time, until the chocolate chips have melted and are warm and smooth.