Preheat oven to 350F.
In a large bowl, stir together brown sugar, butter, vanilla, salt, and egg. Add flour and pumpkin pie spice; mix well.
Spray mini muffin cups with nonstick spray.
Spoon batter into muffin cups filling cups about two thirds of the way.
Bake for 13-15 minutes until toothpick inserted in the center comes out clean.
Cool for a few minutes before removing the Blondies from the muffin cups.
Allow the Blondies to cool completely before frosting.
Spoon the frosting into a piping bag fitted with a large star tip.
Pipe frosting onto the Blondies.
Sprinkle pumpkin spice on top of the frosting.