Preheat oven to 350 degrees F. Line a 9x9 baking pan with foil. Grease the foil with baking spray or butter. Set aside.
In medium bowl mix together the flour, cinnamon, baking powder and baking soda. Set aside.
Add the brown sugar and butter to a medium sized saucepan. Cook over medium low to medium heat for about 5 minutes or until melted and smooth. Remove from heat and cool for approximately 10 minutes.
Add the eggs and vanilla. Stir to combine.
Stir in the flour mixture. Spread the batter in the prepared baking pan.
Bake at 350 degrees F for 25-30 mins. Bars will be very gooey in the center at 25 minutes. They will be more cake like at 30 minutes. Remove from the oven and cool in the pan for 5 minutes. Mix together the sugar and cinnamon for the topping in a small bowl. Brush the top of the bars with the melted butter and sprinkle with the cinnamon sugar mixture. Lift the bars out by holding the foil and set to continue cooling on a wire rack.
Can also be made in an 8x8 baking pan also. The bars will be thicker and bake for about 30 minutes for gooey bars.