01 -
In a small saucepan, melt 8 Tbsp butter over medium-low heat. Swirl occasionally until butter turns amber and smells nutty (about 5 minutes). Pour into a stand mixer bowl with remaining 4 Tbsp softened butter. Let sit 5 minutes.
02 -
Add sugars to the butter and beat with paddle attachment for 1 minute. Mix in egg, egg yolk, and vanilla until combined.
03 -
Add baking soda, cream of tartar, salt, and flour. Mix until just combined. In a separate bowl, mix sugar and cinnamon for coating.
04 -
Line baking sheets with parchment. Scoop dough into balls, roll in cinnamon sugar, and place 2 inches apart on sheets.
05 -
Bake at 350 degrees F for 10-12 minutes, rotating pans halfway. Cool 5 minutes on sheets before transferring to racks.
06 -
Sprinkle leftover cinnamon sugar on warm cookies if desired.