Measure and keep all the ingredients ready. Also, preheat the oven to 180 deg C for 10 minutes. Take the butter in a mixing bowl and add powdered sugar.
Beat it with a whisk and mix well until the sugar is completely melted and the mixture is creamy, Then add in Vanilla essence.
Give a quick mix. Place a sieve over a bowl, add whole wheat flour and custard powder. Sift the flour.
Now Start to mix the dough with your hands gently until you get the soft dough consistency. Once the soft dough consistency is reached, keep the cookie dough in the refrigerator for 20 mins(optional step). In the meantime, line the cookie tray with a cookie sheet/parchment paper.
After 20 mins, take the cookie dough from the refrigerator and start making balls and flatten it using your palms. Mark lines with a fork. Arrange the cookies, and bake in the preheated oven for 15 minutes (baking time depends on the size of the cookies and oven) at 180° C till cookies are browned at the bottom. Allow to cool in tray entirely and serve the cookies.