Set your oven to 180°C and grease an oven proof dish
Place the butter into the dish and pop it into the oven (while it's heating up) until the butter has melted
In a bowl, combine the flour, ¾ cup sugar, baking powder, milk and egg
Once combined, pour into the dish with the melted butter. You don't need to stir it.
In a bowl, combine the peaches, ⅓ cup sugar, vanilla, cinnamon and nutmeg. If you don't have nutmeg, feel free to use something like all spice, or just use cinnamon
Once combined, gently spoon the peaches into the dish. If you'd like the peaches to stay on the top of the dessert, don't mix. But if you'd like them to be inside the cake, then fold them very gently into the mixture
Sprinkle with brown sugar
Bake for 50min, until the bake is golden on top. You can also pop the grill on for a few minutes if you would like it to get a little crispy