Take a pan, pour in the milk along with the poppy seeds and bring it to a boil. Then remove from the heat and let it cool for 20-25 mins.
Preheat the oven to 176 degrees celsius. Also grease a cake tin and lightly flour the inside of the tin.
Take a bowl and put in the sugar and butter, whisk them together with the help of an electric mixer. Then gradually add in egg yolks, vanilla, poppy seed-milk mixture and continue beating till this mixture is smooth.
Next add in flour, salt and baking powder into this mixture. Mix it well and keep aside.
Now take a small bowl and whisk the egg whites till they are stiff. Gently fold this into the batter.
Carefully pour this batter into the cake tin and bake for 50-55 mins till a toothpick inserted into the center comes out clean.
Once cooked, let it cool on a rack. Then dust the icing sugar on top and cut in slices and serve.