Preheat your oven to 350°F (175°C).
Line your baking sheets with parchment paper.
In a medium bowl, whisk together the flour, salt, baking powder, and baking soda. Set aside.
In a large mixing bowl, cream the butter, granulated sugar, and dark brown sugar together until light and fluffy.
Beat in the eggs one at a time, then add the vanilla extract and mix until combined.
Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined.
Fold in the white chocolate chips, chopped macadamia nuts, and white chocolate M&M's.
Scoop rounded tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart. Press additional M&M's on top of each dough ball.
Bake for 10-12 minutes, until the edges are golden brown and the centers look slightly underbaked.
Cool on the baking sheet for 5 minutes before transferring to a cooling rack.
