In a bowl, combine all the ingredients until crumbly. Set aside
With the rack in the middle position, preheat the oven to 350°F (180°C). Line 12 muffin cups with paper or silicone liners.
In another bowl, combine the flour, coconut, wheat germ and baking powder.
In a third bowl, whisk together the sugar, coconut milk, oil and egg. Stir in the dry ingredients until just moistened, then gently fold in the mango and blackberries. Divide the batter among the muffin cups and sprinkle each with 2 tsp of the topping.
Bake for 25 minutes or until a toothpick inserted into the centre of the muffins comes out clean. Let cool on a wire rack.
The muffins are best consumed the day of, but they will keep for 2 days. Delicious with mango butter (see recipe).