In a heavy bottom pan, dry roast all the masala ingredients on a low flame till fragrant. Let it cool for sometime and then grind to a fine paste.
To make the dough, mix together all the ingredients till well blended and then using your hands knead the dough for 7-8 minutes till it is smooth and stretchy. If using kitchen aid or other stand mixer, mix the ingredients using the ballon attachment and once mix, use the dough attachment to knead the dough till smooth for about 5 minutes or so. You can also knead the dough using a food processor's kneading blade. Put all the ingredients in the bowl and knead till the dough forms a smooth ball. Once the dough is kneaded, grease it with olive oil and set aside in a large bowl loosely covered with a muslin cloth or cling film the bowl. Let the dough stand for at least one hour or till double in size.
While the dough is rising, prepare your filling. In a kadhai, heat oil and add sliced onions to it. Saute till transparent and at this point add the tomato, saute till tender. Add 2 tbsp of Xacuti masala and chicken. Fry for 2-3 minutes and then add 2-3 tbsp of water, cover and cook till chicken is tender. Set aside for cooling.
Once the dough is done rising, press the dough to knock back all the air and knead for 2 minutes. Distribute the dough in 6 equal parts and make rounds balls. Set aside for 5 minutes.
Taking one ball at a time, press them down and put 3-4 tbsp of stuffing in the middle just like you stuff your paranthas and seal well. Roll in a round again and keep in a greased pan. You can use a square pan and keep them 2 inches if you want perfect rounds but I really like the idea of pulling buns out like pav and hence I keep them together or use a round pan for baking.
Repeat for all 6 balls and then set aside for 30-45 minutes for proofing. Once almost double or when the dough doesn't bounce back when touched with a finger, heat your oven at 190C.
Glaze the buns with a beaten egg or water + oil. Sprinkle some sesame seeds on top and bake for 18-20 minutes till the buns are golden brown.
Serve warm with tea, soup or milk depending on the time of the day you are having these :)