Combine peaches, brown sugar, lemon juice, vanilla extract, and cinnamon in a bowl. Stir and set aside.
In a separate bowl, combine melted butter, flour, granulated sugar, baking powder, salt, and buttermilk. Stir until smooth. Set aside.
Pour peach mixture in a 13x9 baking dish. Add cake mixture on top and spread over the top.
Bake in preheated oven for 40-45 minutes or until cake mixture is golden on top.
When spreading the cake mixture on top, it will not be enough to get to the corners of the baking pan. That is totally fine. We want those peaches in the corner to get nice and bubbly.Yellow cling peaches are the best kind for this cobbler.