Preheat the oven to 350° F. Line a 9×13 inch baking dish with parchment paper.Add 1 1/2 sticks (12 tablespoons) butter to a skillet set over medium heat. Allow the butter to brown until it smells toasted, about 2-3 minutes. Remove from the heat. Pour the brown butter into a mixing bowl. Add the remaining 1/2 stick (4 tablespoons) butter. Let cool for 5 minutes. To the butter, add the brown sugar, maple syrup, apple butter, egg, and vanilla, Beat until creamy. Add the flour, baking powder, cinnamon, and salt. Fold in chocolate chips and chunks/pecans.Spread the dough into the prepared dish. Bake 18-22 minutes, until the edges are just setting and the center is still doughy. Let cool.To make the glaze. Melt together the butter and maple syrup in a small pot over medium heat. Remove from the heat and whisk in the powdered sugar, vanilla, and a pinch of salt.Drizzle the glaze over the bars. Let set for 5 minutes. Cut into bars, snack, and enjoy!