Place the sugar in a large mixing bowl, and add the sugar.

Whisk until smooth.

Add the baking powder and cornstarch and whisk again.

Add the yogurt and whisk until all the ingredients are well combined.

In another clean bowl, beat the egg whites until stiff peaks form.

Fold the whipped egg whites into the batter.

Add the chocolate chips and mix gently.

Pour the batter into an 8-inch cake pan lined with parchment paper. Bake at 170°C/350°F for 1 hour.

Dust with powdered sugar.

Serve and enjoy!