Snickerdoodle Bars

2 sticks unsalted butter
1 c. dark brown sugar
1/2 c. granulated sugar
1/2 tsp. baking soda
1/2 tsp. cinnamon
1/2 tsp. salt
2 large eggs
1 tsp. pure vanilla extract
2 1/4 c. flour
1 tsp. cinnamon-sugar, to sprinkle on top

Preheat oven to 350 degrees. Take out a nonstick 13x9" baking dish and set aside. Cream butter and sugars with an electric mixer at high speed until fluffy. Add baking soda, cinnamon and salt, then mix at low speed to blend. Add eggs and vanilla extract and beat at medium speed until just mixed. Add flour and mix on low speed until blended. Scrape dough into pan, smoothing it in an even layer. Bake until lightly golden brown and set in the center, for about 30 minutes. Transfer pan to a cooling rack and if desired sprinkle cinnamon-sugar over warm bars and then let cool before slicing.