3 Days prior to baking separate yolks from egg whites. Age egg whites for 3 days in a sealed container in the fridge. Separate eggs when cold.
1 Hour prior to mixing remove egg whites from fridge and allow to come to room temperature. Room temperature eggs will give a better meringue.
Measure dry ingredients on a kitchen scale. Measuring cups can be used, but as macarons are notoriously fussy it is best to measure by weight.
In a large mixing bowl combine dry ingredients and sift 3 times. Discard any small bit that remain in the sifter. Sifting helps ensure a smooth shell.
In a stand mixer, using the whisk attachment, whisk eggs until foamy.
Add brown sugar, granulated sugar, cream of tartar, vanilla extract, butter extract, and bourbon to egg whites to form stiff peaks. You should be able to hold the bowl upside down without any of the meringue pouring out. Don't over or undermix. Under=Cracked Top / Over=No Ridges
Fold in sifted dry ingredients to the meringue in 3 parts with a spatula. Scrape the bottom center of the bowl and fold to the side of the bowl. Continue folding until all dry ingredients are combined and batter resembles smooth moving molten lava.
Transfer batter to a pastry bag.
Place silpat on cookie sheet and pipe onto macaron silpat.
Rap cookie sheet on counter top 3 times. This release air bubbles and ensures a smooth top.
Let sit 45 minutes before baking. Baking immediately will cause the cookie to spread.
After 30 minutes pre-heat oven to 300°.
Bake for 15 minutes or until legs are well formed. (Only bake one sheet at a time)
Remove silpat from cookie sheet and carefully transfer too cooling rack, without disturbing the cookies.
While cookie shells cool work on the filling.