Preheat oven to 350 F. Grease two 9x13 inch rectangular pan and line them with pre-measured parchment paper. Grease the parchment paper. In a large bowl, combine the flour, baking powder, salt, and sugar.
In another bowl, whisk together the egg yolks, water, oil and vanilla; Add to the flour mixture and beat for about three minutes until smooth. Set aside.
In another large bowl or on a bowl of stand mixer with clean beaters, beat egg whites and cream of tartar on high speed until firm peaks form. Using a rubber spatula, gently fold a fourth of egg whites into the yolk batter, then fold in remaining whites. Divide batter in half; Gradually fold the ube flavoring into one half of the batter. We now have two batters: ube and vanilla.
Pour the batters into the two prepared pans. Bake at 350 F for 12-15 minutes or until a toothpick inserted in the middle of the cake comes out clean. Please note that one cake may bake faster than the other so you need to watch closely. Transfer the cakes onto wire racks, including the parchment paper backing. Let cool completely.
To Assemble the Cake
After the cakes have cooled, we need to remove the parchment paper backing on them. To do this, sprinkle some powdered sugar on top of a cake. Top the cake with a piece of parchment paper that is about the same as its size. Top it with a baking pan that has the same size as well. Invert everything over, and carefully peel off the parchment paper on the cake. Reposition the parchment paper, top the cake with another baking pan, and invert again so that the cake is facing up as before. Repeat with the other cake. The cakes should be resting on inverted baking pans.
Spread the buttercream on top of the heavier cake. Carefully lift the other cake and place it on top of the buttercream. If desired, trim the edges of the cake. Cut the cake vertically in half, then cut into seven portions horizontally. You can either serve them on a platter if serving immediately, but I like to wrap them individually in plastic wrap for gifting or storing. Enjoy! These can be stored at room temperature, covered or wrapped for up to 2 days. For longer storage, keep them in the fridge for up to a week.
For the ube buttercream
In a small bowl, whisk the softened butter until fluffy. Add in the sugar and whisk until incorporated. Add the milk and ube flavoring and whisk mixture together until smooth and spreadable. You can adjust the amount of milk to achieve desired consistency. You may add more sugar if mixture is too thin.
Cake slices are best stored individually wrapped in plastic wrapper or wax paper and kept at room temperature for up to two days.
The ube flavoring used is liquid/paste type.
Store wrapped cakes in the fridge for up to a week.
Ube-Vanilla Chiffon Cake
Amount Per Serving
Calories 320Calories from Fat 153
% Daily Value*
Saturated Fat 6g38%
Vitamin A 324IU6%
* Percent Daily Values are based on a 2000 calorie diet.