For the crust:

1. Line an 8" square baking dish with parchment paper. Include an overhang of parchment paper on the sides to help easily remove bars after baking. Spray parchment with baking spray.
2. In food process, pulse 60 grams (¼ cup) macadamia nuts until crumbly like very course sand, about ten 1-second pulses.
3. Add 130 grams flour, 30 grams powdered sugar, salt, and zest of 1 lemon to food processor. Pulse until combined, about five 1-second pulses.
4. Add butter cubes to flour mixture and pulse into butter is size of large peas, about ten 1-second pulses.
5. Pour flour-butter mixture into prepared baking dish and press, as evenly as possibly, into pan.
6. Refrigerate crust for 30 minutes.
7. While in the fridge, preheat oven to 350°.
8. After refrigeration, bake crust for 20 minutes in preheated oven.

For the filling:

1. Spread remaining macadamia nuts (110 grams) on cookie sheet. Roast for 8 - 10 minutes until lightly browned in 350° oven. (you can add them in the oven with the baking crust). Set aside to cool.
2. Roughly chop cooled macadamia nuts.
3. In medium bowl, whisk eggs.
4. To the eggs, add granulated sugar, 3 tablespoons flour, baking powder, zest of 1 lemon, and lemon juice. Whisk thoroughly.
5. Stir in chopped, toasted macadamia nuts.
6. Pour macadamia lemon mixture over hot, pre-baked crust.
7. Bake approximately 25 minutes until set (filling will still have very slight jiggle.

Final assembly

1. Cool lemon squares completely on rack.
2. While cooling, add remaining nuts and powdered sugar to food processor. Pulse until nuts are finely chopped.
3. Once squares are cool, dust with remaining sugar/nut mixture.
4. Use parchment sling to remove from pan and cut into bite-sized squares.