In a mixer, fitted with a paddle, cream the sugar and the butter until light and fluffy. Add the maple syrup and eggs. Mix to incorporate. Add the pumpkin and mix to incorporate. Sift together the flour, baking powder, salt, cinnamon, allspice, nutmeg and cloves. Add the dry ingredients to the batter and mix well. Drop rounded tablespoonfuls onto ungreased cookie sheets. Bake for 10 minutes, or until lightly golden brown around the edges. Cool on racks. When cool, ice with the cream cheese frosting.
For the Frosting: In a mixer, fitted with a paddle, add the cream cheese. Beat until light and fluffy. Beat in the powdered sugar until smooth. Add milk and vanilla. Beat until smooth. If frosting is too thick, thin with a little more milk. Fold in the lemon zest. When cookies are cool spread with some of the frosting. Garnish with a whole pecan.