Preheat oven to 350 degrees F. Spray a 9×13 baking dish with non-stick cooking spray; set aside.
In a medium bowl, combined baking powder, salt, cinnamon and flour. This is the dry mixture.
In a stand mixer bowl, cream together butter and brown sugar until light and fluffy, about 5 minutes.
Add eggs one at a time, making sure to incorporate each one.
Add vanilla and beat until smooth.
Add in the dry mixture and mix until it’s just combined.
Pour batter into baking dish and spread evenly with a offset spatula.
In a small bowl mix cinnamon and sugar. Sprinkle evenly over the batter.
Bake for 25-35 minutes or until bars are set in the middle and a toothpick inserted in the middle comes out clean. Cool completely then cut it into bars.