Preheat the oven to 375 degrees F.
Peel and slice the peaches and place in a medium bowl. Mix together the 1/4 cup sugar, brown sugar, cinnamon, and cornstarch. Add to the peaches and mix well.
For the biscuit topping - mix the flour, sugar, baking powder, and salt together in a medium bowl. Add the butter and cut in until the mixture is crumbly.
Mix together the milk and beaten egg add to the flour mixture. Mix just until the ingredients are combined.
Spray a 10 inch cast iron skillet with a non-stick cooking spray. Spread the peaches in the cast iron skillet. Drop the biscuit dough by large spoonfuls over the peach mixture.
Bake for 35 to 40 minutes or until the biscuits are lightly browned and the peaches are tender. Remove from the oven and cool for about 15 minutes before serving. Serve with vanilla ice cream (optional)
Note: This recipe is not overly sweet. If you like a sweeter dessert add additional sugar to the peaches and the biscuit to taste.