Toss the peaches with the sugar, lemon juice, lemon zest, and cornstarch in a large bowl until the ingredients are distributed evenly. Put 6 (4-ounce) ramekins on a sheet pan and spoon the peach mixture into the ramekins, packing the slices in pretty tight so there are no gaps.
In a separate bowl make the topping, rub the cold butter into the flour with your fingers, until the mixture resembles fine bread crumbs. Add the sugar, salt, and cinnamon; stir well, then add the milk to form a loose, scone-type mixture. Roll the dough into small balls and drop them over the fruit. Bake for 20-25 minutes until the crust is golden brown. Cool slightly before serving. Serve with vanilla ice cream.