Add sugar and cardamom in the grinder and grind to a fine powder. Take out powdered sugar in some bowl and keep aside.
Now add oats in grinder and grind to a fine powder. Keep aside.
Take a Kadai in which ghee residue is already placed and sticked all around. Scrape the residue from all the sides and collect in the centre of Kadai.
Add powdered sugar and mix well to make a soft cream.
Now add powdered oats and all purpose flour and mix them.
Don't knead but only try to bring everything together, better with your finger tips.
If the dough is not binding together being dry, add butter milk just a spoon and bind everything together.
Place the dough in refrigerator for 10 minutes and switch on your oven @180°C for preheating.
Take the dough out and start making small balls out of it one by one.
Press each ball gently and keep arranging them on baking tray already lined with parchment paper.
Bake in the middle rack of oven with both rods on for 20 to 25 minutes at oven @180°C / 350F or until the cookies turn slightly brown.
Take the tray out of rack and let cookies turn cool.
Your eggless oats cookies with leftover ghee residue are ready.