Preheat the oven to 350 degrees F. Spray a 9×9-inch baking pan liberally with nonstick spray and set it aside.
In a large bowl, whisk together the browned butter and brown sugar until combined. Stir in the vanilla extract, then add the eggs and whisk until a smooth batter forms. Add the all-purpose flour, baking powder, baking soda, and salt, and stir until the dry ingredients are completely incorporated. Stir in the chocolate chips.
Spread the batter evenly in the greased 9×9-inch pan.
Whisk together the oats, brown sugar, flour, and ground cinnamon until combined. Stir in the melted butter until the mixture is moistened, then crumble it evenly over the blondie batter. Bake the bars for 30 to 35 minutes, or until the center no longer jiggles and the edges are golden. Let cool completely before cutting.