Add oil and sugar in a bowl.
Also add milk in it. Initially we added only 1/2 cup of milk.
Mix them together. Not necessary to dissolve the sugar.
Sieve all purpose flour, baking powder, baking soda and salt into the bowl through a sieve.
Mix the mixture. Add a spoon or 2 of more milk if feels that mixture is too much thick. We need thick mixture but of running consistency. Keep this bowl aside.
Take another bowl & add cocoa powder & 1 tsp milk in it. Mix.
Pour half of the earlier prepared (white) batter into this bowl carrying cocoa milk mixture. Mix.
Now you have two types of batter. One white batter and second dark batter made with cocoa powder.
Open the lid of sandwich maker/toaster & generously grease both it's sides (base & inner lid) with oil. Sandwich maker hasn't switched on yet.
Pour a small spoon of any one batter in all the 4 portions of sandwich maker. Let it be white for us.
Over the white batter, pour a small spoon of dark batter.
Likewise keep on pouring one after the another coloured batter on layer over layer until the portions of sandwich maker are reasonably filled.
Don't forget the extreme corners. They too need to be filled likewise.
Once you have poured requisite quantity of batter in all the 4 portions, take a toothpick and swirl the batter to give a marble effect.
Close the lid of sandwich maker and now switch it on. Toast for about 4 to 5 minutes.
Open the lid of sandwich maker. If the cake is fluffed up and turned brown, switch off the sandwich maker.
Don't take them out immediately. Let them turn slightly cool otherwise they will damage.
Now run a knife on all the edges of cake. Be gentle, don't hurt the toaster. They are generally non stick.
Remove the cake one by one using spatula. Make the second batch likewise with rest of the batter.
Your eggless marble pillow cake is ready.