Lightly grease the inside of a 5–6 quart slow cooker with butter or nonstick spray to prevent sticking and make serving easier.
butter or nonstick spray
In a large bowl, combine sliced peaches, 1/2 cup granulated sugar, 1/4 cup brown sugar, lemon juice, 1 teaspoon vanilla extract, cornstarch, 1 teaspoon cinnamon, nutmeg, and a pinch of salt. Stir gently until the peaches are evenly coated and the cornstarch is dissolved into the juices.
6 cups sliced peaches, 1/2 cup granulated sugar, 1/4 cup light brown sugar, 1 tablespoon lemon juice, 1 teaspoon vanilla extract, 1 1/2 tablespoons cornstarch, 1 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg, salt
Pour the peach mixture into the prepared slow cooker and spread into an even layer. Some extra juice is fine; it will thicken as it cooks.
6 cups sliced peaches
In another bowl, whisk together flour, 1/2 cup granulated sugar, baking powder, 1/4 teaspoon salt, and 1/2 teaspoon cinnamon (if using). Add the cold butter cubes and cut them into the dry ingredients with a pastry cutter, two knives, or your fingertips until the mixture resembles coarse crumbs with some pea-sized bits of butter.
1 cup all-purpose flour, 1/2 cup granulated sugar, 1 1/2 teaspoons baking powder, 1/4 teaspoon salt, 1/2 teaspoon ground cinnamon, 1/3 cup unsalted butter
Pour in the milk and 1/2 teaspoon vanilla extract. Stir just until the batter comes together into a thick, soft dough. If using oats or nuts, gently fold them in.
1/2 cup milk, 1/2 teaspoon vanilla extract, 1/4 cup old-fashioned rolled oats, 1/4 cup chopped pecans or walnuts
Drop spoonfuls of the cobbler batter over the peaches in the slow cooker. You do not need to cover the surface completely; small gaps are fine and create a classic cobbled look.
Cover the slow cooker with the lid. Cook on HIGH for 2 to 2 1/2 hours or on LOW for 3 1/2 to 4 hours, until the peaches are bubbling and the topping is set and cooked through in the center.
To check doneness, insert a toothpick into the thickest part of the topping. If it comes out with moist crumbs but no wet batter, it is done. If it is still doughy, continue cooking for another 15–20 minutes and test again.
Turn the slow cooker to Warm and let the cobbler rest for about 15 minutes. This helps the juices thicken slightly and makes it easier to scoop.
Spoon the warm cobbler into bowls. Serve as is or top with vanilla ice cream, whipped cream, or a spoonful of plain Greek yogurt.
vanilla ice cream or whipped cream