Preheat the oven to 340 degrees F (170 degrees C).
Sift the Self-Rising Flour (200 gram) and set aside. Grease Ikea pan, and set aside.
Beat the Salted Butter (250 gram), Caster Sugar (100 gram), Lemon (1), and Sunkist Orange (3) till light and creamy.
Separate Egg (4) yolks from whites and set both aside.
Add in the Egg Yolks one by one, until mixture incorporated, mix well.
On low speed, fold in the flour, alternating with the Orange Juice (60 milliliter). Mix till well incorporated.
In a clean bowl, whisk in Egg Whites until foamy at low speed and gradually in the Caster Sugar (50 gram) and beat from medium to high speed till stiff peaks.
Fold the meringue into the yolk batter in 3 portions with a rubber spatula, gently fold the mixture until just combined.
Spoon a layer of the plain batter, about an inch high into the Ikea pan and smooth evenly with a rubber spatula.
Add Organic Chia Seeds (2 tablespoon) into the remaining plain batter and fold well.
Gently scoop batter mixture on top of the plain batter. Smooth the batter evenly again with a rubber spatula.
Bake for about 35 minutes, test with a skewer till it comes out clean.
Leave cake to cool in pan for 15 minutes. Then remove cake and place on wire rack to cool. Serve and enjoy!