Mix the flour(s) in a large bowl. Add ½ cup of the water to the flour and mix with your hand to combine. Add another ¼ cup water and mix again. Continue adding water, a little at a time, until the dough forms a ball. (The dough should take about 1 cup water.)
Now knead the dough vigorously on a clean, unfloured work surface until the dough is moist, soft, and slightly sticky, but doesn’t cling to clean hands or the work surface, about 5 minutes. If the dough is dry, dip your fingers into some water and knead the water into the dough. Put the dough into a clean bowl, cover with a clean, damp kitchen towel pressed directly onto the surface, and let rest at least 10 minutes and up to 30 minutes.
When the dough has rested, prepare a small bowl of all-purpose flour and also flour your work surface. Break off a piece of dough a little smaller than a golf ball. Toss it in the bowl of flour and then roll it between the palms of your hands to make a ball. Set the ball on the work surface and flatten it into a 2-inch disk. Now roll the disk, flouring the work surface and the dough round as needed, into a thin round 5 to 6 inches in diameter. Put the chapati on a plate and cover with a sheet of plastic wrap. Continue to roll all of the dough into chapatis and stack them on the plate, pieces of plastic wrap between them.
Heat a griddle or frying pan (preferably cast-iron) over medium-high heat.
Place a chapati on the heated griddle or in the pan over medium-high heat and cook until the top darkens slightly and you see bubbles begin to form underneath the surface of the dough, about 1 minute. Now flip the chapati with a spatula and cook the other side until you see more bubbles, about 30 seconds.
If working on a gas stove, turn a second burner to high. Using a pair of flat tongs, carefully pick up the chapati by the edge and put it directly onto the burner. Cook until the chapati balloons and browns, 10 to 15 seconds. Then carefully turn the chapati, using the tongs to pick it up by the very edge, and cook until the underside browns and the bread balloons again, 10 to 15 more seconds. Remove the chapati from the fire with the tongs, or slide it off the griddle, put it on a plate, and rub with butter. Serve immediately while you continue cooking the remaining chapatis.
If working on an electric stove, cook the chapati on the griddle or in the pan until bubbles have begun to form on both sides. Then continue cooking the chapati, pressing down the edges of the round with a wad of paper towels as it balloons and turning the chapati in a clockwise motion, until the chapati is well browned and swells like a balloon. Turn and do the same on the other side.