Preheat your oven to 350°F (175°C).
In a large bowl, combine sliced apples with cinnamon and ½ cup of brown sugar. Toss well to coat, and let sit for 10-15 minutes.
In another bowl, whisk together the flour, remaining brown sugar, baking powder, and a pinch of salt. Add melted butter and milk, stirring until just combined.
In a greased baking dish, layer the sugared apples at the bottom and pour the batter evenly over the apples.
Bake for 45-50 minutes or until the top is golden brown and a toothpick inserted in the center comes out clean.
Let cool for a few minutes before serving, preferably with vanilla ice cream.