In a large mixing bowl toss the sliced peaches and sugar together. Let sit in the bowl for 30-40 minutes. This will help the peaches soften and release some juices.
During the last 10 minutes of this process preheat your oven to 400 degrees F and spray an 11x7-inch oval baking dish or a 9x9-inch square dish with cooking spray.
Strain the juices in the peaches bowl to a separate bowl. Return the peaches to the original bowl.
Add ¼ cup of the strained peach juice to a small bowl and add the cornstarch, lemon juice, cinnamon, and vanilla.
Use a fork or whisk to mix until combined.
Pour this mixture over the peaches and toss to combine gently.
Pour the peaches into the bottom of your baking dish.
In a medium mixing bowl, whisk together the flour, sugar, baking powder, and cinnamon.
Add the melted butter and buttermilk and mix until just combined and slightly crumbly. Dollop this mixture over the top of peaches evenly. It’s okay if there are slight gaps where you can see the peaches through it. The topping will come together while baking.
Bake for about 20-24 minutes or until the topping is golden brown.
Remove from the oven and let sit for 25 minutes to let the juices thicken slightly. Your cobbler will still be warm.
Serve with a dollop of ice cream, fresh whipped cream, or just a drizzle of heavy cream, if desired.