1. Preheat oven to 375 degrees. Place peaches, cornstarch, dark-brown sugar, and cinnamon in a large bowl. Toss until well combined. Pour mixture into an 8 1/2-by-11 1/2-inch baking dish.

2. In a large bowl, combine flour, 1/4 cup granulated sugar, the baking powder, and salt. Using a fork, two knives, or a pastry blender, cut in the butter until the mixture resembles coarse meal.

3. Whisk together egg and cream in a liquid-measuring cup. Slowly add this mixture to dry ingredients; mix with a fork until dough just comes together. Turn dough out onto a lightly floured board, and roughly shape into a 12-inch log. Using a bench scraper, cut log into twelve equal portions.

4. Place rough balls of dough on top of peach mixture. Sprinkle with remaining 2 tablespoons granulated sugar. Bake until golden brown, about 45 minutes. Transfer pan to a rack, and let cool slightly. Serve with vanilla ice cream or whipped cream.