1. Cream butter with sugar till creamy and white. Gradually add egg yolks and mix until it doubles in volume.
2. Add condensed milk and golden syrup, mix until combined. Set aside butter mixture.
3. Mix and sift Prima Cake Flour and spekkeok spice powder, slowly fold into the butter mixture until well mixed.
4. Beat egg whites and cream of tartar until stiff peak. Gradually fold into the mixture.
5. Line an 8-inch square tin with parchment paper and grease with butter.
6. Divide the batter into required number of colours you need by mixing each colour in separate bowls.
7. To layer cake, spread 80-90g of mixture in tin and bake in oven at 180°C on bottom heat for 5 minutes. Repeat step for subsequent layers.
8. When top layer is completed cover with a piece of foil and bake for another 10 minutes on top and bottom heat at 180°C.
9. Once baked, turn rainbow kueh lapis out to cool. Keep it over a few days as it usually tastes better as it ages.

Recipe by Chef Ambrose