Preheat oven to 350. Butter a 9 x 5 inch loaf pan and set aside.
In a medium bowl, combine the flour, soda, salt, cinnamon, and nutmeg. Whisk to combine.
Brown the butter by placing it in a small saucepan over medium heat. Let it cook, it will bubble and pop, stirring occasionally until the milk solids start to turn brown. Remove from the heat before they turn too dark, and pour into a heat proof large bowl.
Combine the sugars with the butter. Let it cool slightly or else you could end up with curdled eggs when you add them. Once cooled down, whisk in the eggs until well combined.
Stir in the flour. The mixture will be very thick. Finally stir in the mango and ginger and scrape into the baking pan. Sprinkle the nuts on top evenly.
Bake for 50-55 minutes, or until it pulls away slightly from the edges and is firm to the touch on the top. Cool in the pan 10 minutes then on a rack. Keeps 3 days wrapped.