01 - Preheat the oven to 350°F. Line a 9x9-inch baking pan with parchment paper and lightly grease the paper.
02 - In a large bowl, cream together the softened butter and brown sugar until the mixture is light and fluffy.
03 - Beat in the eggs one at a time. Add the maple syrup and vanilla extract, mixing until the batter is well blended.
04 - In a separate bowl, whisk together the flour, baking powder, baking soda, and salt until evenly distributed.
05 - Gradually add the dry ingredients to the wet mixture, stirring gently just until the flour streaks disappear.
06 - Spread the batter evenly in the prepared pan. Bake for 22 to 25 minutes, or until a toothpick inserted into the center comes out clean.
07 - Allow the bars to cool completely in the pan before applying the glaze.
08 - In a small saucepan, melt the butter with the maple syrup over low heat. Remove from heat and whisk in powdered sugar, vanilla, and salt until smooth.
09 - Spread the glaze evenly over the cooled bars. Allow the glaze to set firmly before slicing into squares.