Preheat your oven to 350°F (175°C). Grease and flour a baking pan.
In a mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
In another bowl, combine the milk, melted butter, eggs, and vanilla extract. Pour the wet ingredients into the dry ingredients and mix until just combined.
In a small bowl, mix together the brown sugar and cinnamon. Fold in the chopped apples.
Pour half of the batter into the prepared baking pan. Sprinkle the cinnamon sugar apple mixture over the batter. Pour the remaining batter on top.
Bake for 45 minutes, or until a toothpick inserted into the center comes out clean. Let cool before serving.