INGREDIENTS:

Batter

• 1/3 cup sifted cake flour
• 3 tablespoons cornstarch
• 1/2 cup granulated white sugar
• 1 teaspoon vanilla extract (I used 1 teaspoon lemon juice instead)
• 3 egg yolks (room temperature)
• 2 whole eggs (room temperature)
• 1 teaspoon Ube extract (McCormick)
• 1 drop food color (McCormick) (optional)

Meringue

• 2 egg whites (room temperature)
• 1/4 teaspoon cream of tartar
• 1 drop ube extract (McCormick)
• 1 tablespoon granulated white sugar

Buttercream Filling & Icing

• 1/2 jar macapuno or coconut preserve, divided
• 1/4 cup butter softened
• 1/2 cup evaporated milk
• 1/4 cup sugar

INSTRUCTIONS: 

1. Preheat oven to 450 degrees F (230 degrees C). Place oven rack in the center of the oven. Grease Swiss Roll tray, line it with parchment paper then grease (you may also use spray with a nonstick vegetable/flour spray).
2. Place the 3 egg yolks together plus 2 whole eggs in a bowl while the 2 egg whites will be placed in a bowl of your electric mixer. Cover with a plastic wrap and allow to come to room temperature. Set aside. As we all know, it’s easier to separate the egg yolks from the whites while they are cold so better do it while getting out the eggs directly from the fridge.
3. In a small bowl, whisk flour and cornstarch. Set aside.
4. In your electric mixer, place egg yolks together with whole eggs and sugar. Beat in high speed for about 5 minutes or until color turns pale yellow. Beat in vanilla extract. Using a spatula mix-in half of flour mixture gently until incorporated. Add the remaining flour mixture and continue mixing until well incorporated. Add food color  (if using) and Ube extract. Mix well.
5. In a separate clean bowl of your electric mixer beat egg whites, prepare the meringue. Add cream of tartar and continue beating. Add slowly one tablespoon sugar and beat until stiff peaks form. Add a drop of  Ube extract, continue beating until the extract is well incorporated with the meringue. Don't over beat.Once the meringue is done, use a spatula and gently fold-in the batter (the batter is the one you made in procedure #4) and add the rest of the meringue until well incorporated.
6. Pour the batter into the prepared pan with a parchment paper. Use a spatula to evenly spread the mixture. Bake for about 6-8 minutes or will spring back upon touching the top of the cake. Remove cake from the oven immediately do not over bake. Sprinkle the top of the cake with confectioners sugar (this helps protect the cake from sticking to the cloth when inverted). Place a clean damp dish cloth in your workplace (the cloth should be same in size of your Swiss Roll tray). Invert cake into the prepared dish cloth (top facing down). Remove parchment paper. Trim all sides of the cake (you can use the trimmed part of the cake later for decorating, just set it aside). Sprinkle the base layer of the cake with a confectioners sugar and roll up together with the cloth (damp dish cloth helps prevent the cake from cracking when unrolled). Place the rolled cake on a wire rack to cool for about 10-15mins.
7. While waiting for the cake to cool, place trimmed edges of the cake in a food processor and process to form crumbs. (If you don't have a food processor ,you can use a knife to cut them nicely into very small pieces as you can). Set aside.
8. Once the cake is completely cooled, unroll it from the cloth. Spread the base with buttercream icing. (Be sure to set aside an icing to cover the cake and for decorating later). Place half of the macapuno to fill the layer. Roll up the cake. Once rolled, spread with butter icing all over and dust it with cake crumb. You can pipe the icing and decorate your cake as you like consuming the remaining macapuno. Transfer to a plate and place it in the fridge to chill... Your Ube  Macapuno Swiss Roll is done!!!
9. Slice and enjoy!