Preheat the oven to 350°F. Spray a 9x15 inch baking sheet with non-stick spray.
In a medium bowl, whisk together the melted butter, sugar, vanilla extract, and milk.
Add the flour, baking powder, and salt, and whisk until smooth.
Pour the batter onto the prepared baking sheet.
Bake for 13-15 minutes, then let cool completely.
Break the cobbler into small pieces and set aside.