In a large bowl or bowl of a stand mixer, combine butter, Swerve Granular, and Swerve Brown. When adding the Swerve Brown, sprinkle it on top of the other ingredients to make sure it evenly distributes when mixing.
Mix on medium-high for 5-6 minutes until fluffy.
Then, add one egg and mix it in on low. Add the second egg, the third, and do the same.
Add vanilla extract, scrape down the sides of the bowl, and mix on low until well combined.
In a small bowl, thoroughly combine the coconut flour, oat fiber (if using), baking soda, and salt. Add the dry ingredients to the wet and mix in on low for 30 seconds until combined.
Fold in chopped macadamia nuts and white chocolate chips.
Lightly spray the bottom of a casserole dish (I used 7x11”) with non-stick cooking spray, then evenly spread the batter into the dish.
Place casserole dish in the oven and bake for 15-20 minutes (highly dependent on your oven), until the edges begin to lightly brown. Do NOT overbake! The middle of the casserole will still be relatively soft/wet, but an inserted toothpick should come out mostly clean. The cookie bars will firm up as they cool.
Place the Keto White Chocolate Macadamia Nut Cookies on a wire rack and let the cookie bars cool completely. (For quicker cooling, after 30 minutes you can place the dish in the fridge.)
Cut into 10 even pieces and serve.
You'll want to store your Keto White Chocolate Macadamia Nut Cookies in the fridge or freezer.