Preheat an oven to 350 degrees F (175 degrees C). Grease an 8x8 inch baking dish.
Mix the flour and brown sugar in a bowl, and cut the butter into the flour-sugar mixture with a pastry cutter or two table knives until the mixture resembles coarse cornmeal. Add the oats, cinnamon, and nutmeg, and stir well.
Place the cubed mango on the bottom of the greased baking dish, and spoon the passion fruit pulp over the mango. Stir to mix and evenly distribute the fruit in the dish. Drizzle lime juice over the fruit. Sprinkle the fruit with the oats topping, making sure it is fully covered. Sprinkle a little extra cinnamon over the top.
Bake in the preheated oven until the top has browned and the fruit is tender, about 20 minutes.