Preheat the oven at 180C. Coat a 12-cup muffin pan with cooking spray.Now to make the streusel.
Combine coconut, 2 tablespoons all-purpose flour, 2 tablespoons brown sugar and 2 tablespoons macadamia nuts in a small bowl. Drizzle with 1 tablespoon oil; stir to combine. Set aside.
Whisk the remaining 3/4 cup plain flour, whole wheat flour, baking powder, baking soda, salt & cinnamon in a medium bowl.
Whisk the remaining 1/2 cup brown sugar, the remaining 1 tablespoon oil, egg, egg white, buttermilk, milk, butter and vanilla extract in a medium bowl until well combined
Make a well in the center of the dry ingredients and pour in the wet ingredients; stir until just combined
Add blueberries and the remaining 3 tablespoons nuts; stir just to combine.
Divide the batter among the prepared muffin cups
Sprinkle with the reserved macadamia topping and gently press into the batter.
Bake the muffins until golden brown and a wooden skewer inserted in the center comes out clean, about 20 minutes.
Let cool in the pan for 10 minutes, then remove from the pan and let cool on a wire rack at least 5 minutes more before serving.
I have used fresh blueberries. If you want you can also use frozen blueberries (NOT thawed). Coat in with 1 Tbsp Plain flour before adding to the muffin.