Preheat your oven to 375℉. Grease your baking dish and set it aside.
In a small bowl, whisk together the ⅔ cup of sugar and corn starch until combined and not lumpy.
⅔ Cup Sugar, 3 Tbsp Corn Starch
Prepare your peaches by slicing them and removing the pits and stems. Skin on or off is your preference and can depend on your species of peach.
3½ Lbs Peaches
In another bowl, whisk together the flour, baking powder, and remaining sugar.
1¼ Cup Flour, ⅓ Cup Sugar, 1 Tsp Baking Powder
Add the cold butter to the flour mixture and cut it together with a fork or pastry cutter, until you have pea-sized lumps like a biscuit dough. Add the milk and stir it together until it combines.
¼ Cup Butter, ⅔ Cup Milk
Add the sugar and cornstarch mix to the peaches, drizzle the lemon juice over it, and stir it all up to combine. Pour this peach mixture into an even layer across the bottom of your baking dish.
3 Tbsp Lemon Juice
Use a spoon or large cookie scoop to scoop the biscuit dough into dollops across the top of the peaches. More smaller scoops will result in a more even cobbler, or larger dollops leave larger biscuits. It will spread a little when baking.
Sprinkle the top of the biscuits with finishing sugar, if you like. Bake the cobbler for about 45 minutes, or until the dough is browned and the peaches are bubbly. Remove from the oven and let cool for 20 minutes, then enjoy!
1 Tbsp Finishing Sugar