In the bowl of an electric mixer fitted with the whisk attachment, whip the butter for 5 minutes on high, until fluffy and white (scrape sides occasionally).
Add confectioners sugar to the whipped butter a cup at a time mixing on high between additions.
Add the maple syrup.
Whip frosting for 2 - 3 minutes.
Spread frosting onto completely cooled cake or cupcakes.
Recipe by I Heart Kitchen at https://www.iheartkitchen.com/maple-buttercream-frosting/