In a mixing bowl, cream butter and sugar. Beat in eggs one at a time. Beat in maple extract.
In a medium bowl whisk together flour, baking powder and salt. Add flour mixture and chopped pecans to butter mixture and beat just until combined.
Pour batter into a 9 inch square pan.
Bake 25-30 minutes until the center is set.
Remove from oven to a cooling rack. Let cool 10 minutes then cut into bars and allow to cool completely.
Frosting
Beat cream cheese, maple syrup and maple extract if using in a small bowl. Add 1 ½ cups powdered sugar and beat until smooth. Add more powdered sugar or syrup to achieve your desired consistency.
Spread over cooled blondies, decorate with pecan halves if desired.