Brown the butter by melting it in a small saucepan over medium high heat. Stir occasionally, and let it cook until the milk solids turn brown and it starts to smell nutty. Immediately remove the pan from the heat (as it can burn quickly), and pour into a 10 inch round baking dish, or a 9” square baking dish. Set aside.
Combine the flour, baking powder, salt, nutmeg, and 1 cup sugar in a bowl and whisk to combine. Pour in the milk, eggs, and vanilla and whisk until a thick batter forms. Pour this over the brown butter in the baking dish.
Top the batter evenly with the mango and sprinkle with the remaining sugar. Place in your preheated oven and bake for 40-45 minutes. If using the almonds, carefully scatter the over the cobbler after 20 minutes of baking. This will keep them from sinking in to the batter and allow them to get toasty and browned. Remove and let cool for 10 minutes, then serve warm.
*You can make this a few hours ahead of time and reheat in a low oven before serving.