In a mixing bowl, cream together the butter and brown sugar until light and fluffy.
Mix in the maple syrup.
In another bowl, whisk together the flour, baking soda, and salt. Gradually add to the butter mixture, mixing until combined.
Drop by rounded teaspoonfuls onto a baking sheet. Bake for 10 minutes or until edges are golden brown. Cool on a wire rack.
For the cream filling, beat together the butter, powdered sugar, and maple syrup until smooth. Spread filling on the flat side of half the cookies; top with remaining cookies.