Ingredients
- Buttercream Icing:
- 2 1/2 cups cake flour, (sifted with baking powder and salt)
- 3 teaspoons baking powder
- 1 teaspoon salt
- 1 cup ube (purple yam), cooked and finely grated
- 3/4 cup milk + 1/8 cup milk
- 1 teaspoon pure vanilla extract
- 1/2 cup light corn syrup
- 7 egg yolks, lightly beaten
- 1/2 cup vegetable oil
- 7 egg whites
- 1 teaspoon cream of tartar
- 1 cup caster’s sugar
- 1 (12 ounce) jar macapuno (coconut preserves) *OPTIONAL – use as filling (available in the UK from specialist Asian stores)
- Egg whites 50 ml
- Refined sugar 100 g
- butter, cold, cut into cubes 250 g
- 2 tsps violet food colouring (or until desired shade is achieved)
Preparation
Step 1
1. Preheat oven to 325 degrees F (165 degrees C). Line bottoms of 3 – 9 inch pans with parchment paper, Do NOT grease. Mix together and sift the flour, baking powder, and salt; set aside.
2. Place grated ube in a large bowl. Mix together 3/4 + 1/8 cup milk and 1 teaspoon pure vanilla; gradually blend into ube until smooth. Blend in light corn syrup, egg yolks, and oil. Beat in flour mixture until smooth; set aside.
3. In a large bowl, beat egg whites with cream of tartar until foamy. Gradually add sugar, continuing to beat until stiff peaks form. Fold 1/3 of the whites into the batter, then quickly fold in remaining whites until no streaks remain. Pour batter into prepared pans.
4. Bake in the preheated oven for 30 to 35 minutes, or until the centre of cake bounces back. Invert pans on a wire rack and let cool upside down. When cool, run a knife around the edges to loosen cake from pans. Fill between layers with coconut preserves, then frost top and sides with butter icing.
5. To make Butter Icing: Combine egg white and sugar until fully incorporated. Place on top of a barely simmering hot water bath (double boiler). Whisk constantly until temperature reaches 65 -70 degrees C. Transfer into a mixing bowl with whisk attachment, whisk until medium stiff. Replace with paddle attachment then beat on medium speed until cold. Gradually add the butter and beat on medium speed until smooth. Add violet food colour.
*omitted food colour on the cake batter to keep flavour and aroma of ube (yam) pure.