Preheat oven to 350 F. Slice apples and mix with 1/2 cup granulated sugar and cinnamon in a large bowl. Spread mixture out into a greased baking dish.
In a medium bowl, whisk together flour, sugar, salt and baking powder. Pour in milk, melted butter and vanilla extract, whisk until smooth. Pour mixture over apples and bake for 50-55 minutes.