Preheat oven to 340°F (170°C). Sift cake flour and set aside.
Mix egg yolks, peanut oil, pandan juice, and vanilla extract until well combined.
Fold cake flour into the yolk mixture gently in three batches.
In a separate bowl, beat egg whites with cream of tartar until foamy, then gradually add sugar while beating until stiff peaks form.
Fold meringue into pandan batter in three portions until just combined.
Pour batter into ungreased 8-inch round cake tin and bake for 40 minutes until a skewer comes out clean.
Cool cake completely on a wire rack, then invert and remove from tin.
For salted egg yolk filling: mash salted egg yolks with butter and condensed milk until smooth.
Whip heavy cream with salt until soft peaks form, then fold in salted egg yolk mixture.
Slice cooled cake horizontally in half and spread salted egg custard between layers and on top.
Chill for at least 2 hours before serving. Optional: top with grated additional salted egg yolk.
Cook this in the app — save it & get tonight’s menu
Get the app