Preheat the oven to 350°F and grease a 9x13 inch baking dish.
Whip butter and brown sugar together for 2 solid minutes, using a handheld or stand mixer.
Add eggs, vanilla, cinnamon, baking soda, and baking powder. Mix well.
Add flour and gently mix in.
Add batter to a prepared dish. Spread out as evenly as possible.
Combine the topping ingredients: sugar and cinnamon and mix together, then sprinkle evenly over the top.
Bake for about 33 minutes.
Take out of the oven and resist the urge to dig right in until it has cooled. The edges will have puffed up more than the center. That is perfectly fine. Once it has cooled, it will take on the delicious and chewy texture. Cut into squares and enjoy!