• Preheat oven to 350 F. In a medium bowl, combine flour, salt and baking powder. In the bowl of a stand mixer, whisk the egg whites on medium speed until frothy. Add the cream of tartar and continue to whisk until egg whites form firm peaks that hold its shape when the whisk is lifted.
• Meanwhile, beat the egg yolks in a bowl until it is slightly thicker. Add the sugar and mix until incorporated. Add water, oil and ube flavoring and mix well.
• Add flour mixture gradually and mix until the batter is smooth. Gently fold the egg whites to the yolk batter in three additions until batter is uniform. Pour batter into a prepared 10 inch tube pan. Bake for 60-65 minutes, or until a toothpick inserted in the middle of the cake comes out clean. Invert cake on top of an overturned mug and let cool.
• To unmold cake, loosen sides and bottom with a knife. Using your hands, gently push the cake away and downwards from the sides of pan. Remove gently and invert to a serving plate.

Make the Ube Icing

• Whip the cream cheese using a mixer until it soft and smooth. Set aside.  
• In a clean bowl of your mixer, add whipping cream and icing sugar. Whip until cream is wavy and  slightly thick. Add the ube extract and continue to whip until firm peaks form. Gently fold cream to the whipped cream cheese. Spread on cake.