Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan.

In a medium saucepan, combine brown sugar, water or apple juice, cornstarch, lemon juice, vanilla extract, ground cinnamon, ground nutmeg, and salt. Stir until well combined, then add sliced apples. Cook for 3-5 minutes until apples soften slightly and sauce thickens.

Pour the apple filling into the prepared baking pan, spreading it out evenly.

In a large mixing bowl, whisk together flour, white sugar, baking powder, and salt. Make a well in the center and add milk and melted butter. Stir gently until just combined.

Pour the cobbler topping over the apple filling in the baking pan, spreading gently. Sprinkle ground cinnamon over the top if desired.

Bake for 38-40 minutes until the topping is golden brown and a toothpick inserted into the center comes out clean.

Allow to cool for at least 15 minutes before serving.