In a large mixing bowl, combine the flour, baking powder, baking soda, salt, yogurt, and water to form a soft dough. Cover and let it rest for 2-3 hours.
In another bowl, prepare the stuffing by mixing mashed potatoes, paneer, green chilies, coriander leaves, cumin seeds, red chili powder, and chaat masala. Mix well and set aside.
Divide the dough into equal portions and roll each portion into a ball.
Flatten the dough ball slightly, place a spoonful of stuffing in the center, and seal the edges to enclose the filling.
Roll out the stuffed dough ball gently to make a thick disc.
Heat a tawa (griddle) and cook the kulcha on both sides until golden brown spots appear.
Brush the kulcha with butter and serve hot with chole (chickpea curry) or yogurt.