Grease and line a 20cm square baking pan. Preheat oven at 200°C.
Cream butter and 110g sugar until light and fluffy. Add egg yolks four at a time, beating well after each addition. Add the final five yolks and beat until well mixed.
Add pandan juice, essence, coconut milk, condensed milk and stir in colouring to mix.
Whisk egg whites, 100g sugar and cream of tartar in a clean mixing bowl until the egg whites are just stiff. Fold gently into the pandan batter in batches with a large metal spoon.
Pour in six tablespoons of the batter into the prepared tin. Level the surface, then bake for 10 minutes or until golden brown. After each layer is done use a glass with a broad flat base to lightly press the surface to release any trapped air bubbles. Continue the baking until all the batter is used up.
Bake the completed cake under the grill at 200°C for an extra 6-7 minutes or until lightly golden on the surface.