01 -
Preheat the oven to 175°C (350°F) and grease a 9×13 inch baking pan.
02 -
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth and fluffy.
03 -
Add the eggs, sour cream, and vanilla extract to the creamed mixture, stirring until well combined.
04 -
In a separate bowl, whisk together the flour, baking powder, baking soda, ground cinnamon, and salt.
05 -
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
06 -
Spread the batter evenly into the prepared baking pan.
07 -
In a small bowl, mix together additional cinnamon and sugar for topping, then sprinkle it evenly over the batter.
08 -
Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean. Remove from oven and allow to cool completely.
09 -
For the frosting, whisk together powdered sugar, milk, and vanilla extract until smooth.
10 -
Spread frosting evenly over the cooled bars before serving.