Preheat oven to 350 degrees. Add 1 tablespoon of butter to a 9 x 13 baking dish. Transfer dish to the oven as it preheats. Remove dish from the oven once butter has melted. Set aside.
Peel and slice peaches then cut each slice in half. Transfer the buttered baking dish. Squeeze lemon juice over the top then sprinkle with sugar, corn starch, cinnamon and salt. Gently stir until coated then spread evenly in the pan.
To a medium mixing bowl, melt butter then add flour, granulated sugar, baking powder, salt, cinnamon and vanilla extract. Mix to a soft cookie dough-type batter forms. It should hold together when pressed with your fingers but not be overly wet.
Sprinkle the dough over the top of the peaches using your fingertips. Leave small areas uncovered around the edges so the fruit juices bubbles up.
Bake 30-35 minutes or until golden and bubbly. Sprinkle turbinado sugar over the top and pop under the broiler for a minute or so until it’s lightly crisp. NOTE: watch close so the sugar topping doesn’t burn.
Remove from the oven. Cool 20-25 minutes. Serve warm or room temperature scooped into bowls and topped with vanilla ice cream.