Preheat oven to 350°. Lightly grease or spray a 13x9 baking dish.

Cream butter in a large mixing bowl.

Beat in brown sugar, eggs and vanilla until smooth.

In a separate bowl, whisk together the flour, baking powder and salt.

Add the flour mixture to the butter mixture and mix until thoroughly combined. Do not over mix.

Spread the batter evenly in the prepared baking dish.

In a small bowl, combine the white sugar and cinnamon.

Sprinkle the mixture evenly over the batter.

Bake for 25 - 30 minutes or until the surface springs back when gently pressed.

Cool on a wire rack.

Cut into squares and enjoy :)