Preheat the oven to 400° F (205° C.) Line 12 muffin cups with papers or silicon baking cups.
Mix the dry ingredients: In a large bowl, add the flour, baking powder, salt, cinnamon, cardamom, and brown and white sugars. Stir with a large spoon until these are fully combined.
Mix the wet ingredients: In a medium bowl, add the oil, eggs, vanilla, and milk. Whisk until the wet ingredients are fully combined.
Make a well in the center of the dry ingredients and pour in the wet ingredients. Stir gently with a spoon until the batter is almost completely combined. Add the chopped mango and continue stirring until it is incorporated, begin careful not to overmix.
Make the Crumble and Bake:
In a medium bowl, add the flour, brown sugar, salt, cinnamon, cardamom, and chopped hazelnuts. Stir until all of these ingredients are well combined. Next, add the butter and mix by hand until the butter is fully incorporated and the mixture forms crumbs.
Pour the muffin batter into the muffin cups. Top each cup of batter with the crumble, dividing it equally among the 12 cups. Bake at 400° F (205° C) for about 16-18 minutes, or until the tops of the muffins spring back when touched and the crumble is lightly browned.