Generously brush inner sides and bottom of round (8 ½ inch/diameter) baking pan with the oil. and prepare steamer by heating water in low heat.
In a large bowl, combine glutinous rice flour, coconut milk, and condensed milk. Stir until smooth and well blended. Add sugar and salt and stir again until sugar is dissolved.
Divide the batter evenly into three bowls.
In one bowl, add Ube extract and ube halaya, stir until color is uniform. In another bowl, add Langka extract and stir until color is uniform. The remaining portion will remain the same.
Pour ube flavored batter into the prepared baking pan. Steam for about 30 minutes or until set and toothpick inserted comes out clean.
Next, gradually pour langka flavored batter over ube layer. Steam for about 30 minutes or until set and toothpick inserted comes out clean.
Then, gently pour white/plain batter over purple layer. Steam for about 30 minutes or until set and toothpick inserted comes out clean. Remove pan from steamer and allow to cool down completely.
Pass a knife around the sides of the foil pan to loosen the cake. Place a wide, flat serving dish over cake pan and gently invert. Tap the pan a few times to release the sapin-sapin onto the serving dish. Sprinkle with Latik and Voila! Bon Appetit!