Rinse the eggplant and pat dry. Then make few slits all over the eggplant with a knife. In 3 of those slits, insert a large clove of garlic. Brush it with little oil all over.

Put the eggplant directly on heat and roast, turning often for around 10-12 minutes until completely roasted.
Once roasted (to check if its done, insert a knife inside the eggplant, it should go easily) use a pair of tongs to remove the eggplant from heat and cool.

Once cooled, remove the skin. Meanwhile also chop the roasted garlic.

Transfer the roasted eggplant to a bowl and mash using a fork or potato masher. Set it aside.

Heat oil in a pan on medium heat. Once the oil is hot, add ginger garlic paste and green chili. Saute until they start changing color, around 2 minutes.

Then add in the chopped onion and cook for 2-3 minutes until softened. Don't brown them.
Add the chopped tomatoes and mix. Cook the tomatoes for around 5 minutes.
Add the red chili powder, turmeric and garam masals and mix. 
Also add the coriander powder and salt and mix to combine.
Cook until very you notice oil oozing out of the masala.
Add green onion and green garlic and mix well. Cook for 1 min.

Serve baingan bharta hot with fresh bajara rotis and chhas.