Measure and keep all ingredients ready. Also preheat the oven to 180 deg C for 10 minutes. Take 3/4 cup of oats in a blender and grind it to a slightly coarse powder. If using whole oats for making cookies, skip this step.
Take the butter in a vessel and melt it. Once the butter is melted, switch off the flame and add vanilla essence. Now add the boiled milk and mix it once again. Give a quick stir. Then add brown sugar to it.
Mix well until the sugar is completely melted. In a mixing bowl, take the grounded oats flour and add cocoa powder, wheat flour, salt and baking soda to it. Mix well. Then add the butter sugar mix to the dry ingredients.
Start kneading the dough with your hands gently and continue kneading until you get the non sticky dough consistency. Once the non sticky dough consistency is reached, keep the cookie dough in refrigerator for 10 mins. In the meantime, line the cookie tray with a cookie sheet/parchment paper. After 10 mins, take the cookie dough from the refrigerator and start making balls and flatten it using your palms.
Arrange the cookies in parchment paper, place chocolate chip over the cookies if desired and bake in the preheated oven for 25 -30 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 for 5 minutes and serve the cookies.