Using the palm of your hand, push the dough away from you 4-5 times until its smooth. Roll into a ball and flatten it into a disk. Wrap in clingwrap and refrigerate.
Keep a 7" pie pan handy and preheat the oven to 180C. In a large bowl, toss the diced peaches, sugar and rosemary with cornstarch. let rest for 10-15 minutes.