Peel and slice peaches. Place 1 cup of the sliced peaches into a Dutch oven. Add the sugars and butter. Cook until soft and mixture bubbles. Smash the peaches. In a small bowl, mix some hot mixture in with a thickener (cornstarch or tapioca) and add it back to pot a bit at time until you get a nice consistency (I like my fresh (or frozen) peaches to stay firm, so I add the majority later to be cooked in the pie). Let the cooked filling cool while you roll out your pie crust. When cooled, add the balance of the sliced peaches (in the summer, I omit the brown sugar and add a ¼ cup of orange juice to make a nice “bright” pie).