In a mixing bowl with an electric mixer, cream together the butter and sugars for 3 minutes or so until very light and fluffy.
While you cream the butter and sugar, gather the rest of your ingredients and whisk together the flour, cornstarch, salt, and baking powder.
To the butter/sugar mixture, add the eggs and extracts. Mix until smooth, scraping down the sides of the bowl once or twice.
Add the flour mixture a little at a time until a very thick dough forms. Don't overmix. Add the chocolate chips and macadamia nuts.
Scoop the dough into 3 tablespoon cookies using a cookie scoop. Freeze the dough balls (all together on a baking sheet, then transfer to a plastic bag), or chill for 30 minutes.
When ready to bake, preheat the oven to 375F. Arrange the dough balls 2 inches apart on a baking sheet with parchment paper, a silicone baking mat, or cooking spray. Bake the cookies for 9-11 minutes (for large cookies, decrease the time for smaller cookies) until just golden at the edges but still soft in the center.
Allow the cookies to cool for 10 minutes on the baking sheet, then transfer to a wire rack to cool completely. Devour.