Pre-Heat oven to 400F and line a baking sheet with a silicone mat or parchment paper.
In a large bowl mix together the flour, sugar, baking powder and salt. Transfer to a food processor. Add in the semi frozen butter cubes. Process until you get sandy crumbs.
Place the flour and butter mixture back into the large bowl you used to mix the flour. Make a deep well in the middle of the flour mixture.
In a separate bowl or large cup mix together the cream, egg, vanilla and calamansi juice. Pour the mixture into the hole. Using a spatula or wooden spoon mix until you get a shaggy dough. Transfer to a clean work surface.
Use your hands to very lightly kneed the dough just so that it sticks together. Form the dough into a small square. Then using a knife or pastry cutter cut into 4 portions.
Take one portion and flatten it out to about ½ a cm trying to make it level and even as possible. Place on a prepared baking tray. Spread 1 tablespoon of Langka jam all over the dough. Repeat the same process for the second and third layer.
With the forth layer place it on top but don't put any jam on. Cut the square in half and then cut each half into thirds.
Brush each Langka Scone with leftover cream. Then top with some polvoron.
Place each Langka Scone on a baking tray with a silicone mat or parchment paper. To keep the layers from moving place a tooth pick at each end of the scones.
Bake at 400F for 20 minutes. Leave to cool down. It will all stick together once it comes to room temperature.