Take a tray (8 inch baking dish) and brush butter on it.
Then put a parchment paper on it and keep this aside.
Take a bowl and add butter into it.
Beat it for a few seconds.
Then add blended sugar and beat again.
Add eggs one at a time and beat them well.
Next, add vanilla essence and beat well.
Take a bowl and put flour and baking powder.
Then sift it.
Next, add the sifted flour to the bated mixture and add pinch of salt.
Then, mix well.
Add warm milk into it and mix well.
Transfer the batter to baking dish.
Then bake it in preheated oven at 180°C for 30 to 35 minutes.
After baking it, let it cool completely.
Then cut squares.