Roughly chop the macadamia nuts and add to a medium mixing bowl along with the rolled oats, and dried or softened mango. Stir together and set aside.
In a small mixing bowl, stir together flour, baking powder, baking soda, salt and allspice until evenly distributed. Set aside.
In a large mixing bowl or in the bowl of your stand mixer, add softened butter, brown sugar and lime zest, beat with the paddle attachment on medium speed until light and fluffy, about 1-2 minutes. Add egg and vanilla extract, and continue beating until thoroughly combined, another 1 - 2 minutes.
Lower the mixer speed to stir and slowly add the flour mixture, mix until just combined. Add the oat mixture and stir until evenly distributed. Give the mixture a final stir with a spatula, scraping the side and bottom of the bowl to ensure even mixing.
Use a large ice cream scoop to divide the batter. Refrigerate the cookie dough and preheat the oven in the mean time.
Preheat oven to 350°F. Bake for 15-16 minutes, rotate the baking sheet at the 10 minutes mark.
Remove from the oven and allow cookies to cool on the baking sheet for 5 - 10 minutes, then remove them to cool completely on a wire rack.