Preheat oven to 375 degrees F. If you haven't already done so, toast the coconuts and nuts**
Mix flour, baking powder, baking soda and salt; set aside.
Cream the butter in the bowl of stand mixer with paddle on low speed for 30 seconds. Add the sugars and beat the mixture until light and fluffy, 2-3 minutes, scraping sides of the bowl. Reduce the speed and add the egg and egg yolk and mix until combined. Scrape bowl and mix in the vanilla.
By hand or using lowest speed of stand mixer, stir in the flour mixture until combined. Add white chocolate, nuts and cooled toasted coconut and stir until mixed.
Divide dough into 16 portions (or use a medium cookie scoop and get about 30), each about 3 tablespoons (or use #24 cookie scoop). Arrange 2 inches apart on prepared baking sheets, 8 dough balls per sheet. (Smaller baking sheets can be used, but will require 3 batches.)
Bake cookies 1 tray at a time until cookies are golden brown and still puffy, and edges have begun to set but centers are still soft, 10 to 14 minutes, rotating baking sheet halfway through baking. Transfer baking sheet to wire rack to cool. Makes 16 big cookies