Add vinegar in slightly warm milk and keep aside undisturbed. It will be our buttermilk.
Boil water in a saucepan and place a bowl on it.
Put dark chocolate and butter in it.
Let the chocolate completely melt. You can melt the chocolate+butter in microwave as well.
Remove the bowl from the boiling water saucepan and add buttermilk.
Give it a good mix.
Add brown sugar and mix well.
Then add cocoa powder, all purpose flour and baking soda.
Mix well but don't overdo.
Place this bowl in refrigerator for 10 minutes.
Thereafter scoop out on the baking tray lined with greased butter paper or silicon mat. Keep them as a distance because they are going to spread on baking.
Put the tray in refrigerator for 15 minutes.
Bake in preheated oven @180°C for 20 minutes.
Bring the tray out of the oven and let the cookies cool down completely.
Eggless Brownie Cookies are ready to enjoy.