Beat shortening, 1 cup butter and sugar in a large bowl at medium speed for 2 to 3 minutes or until smooth and fluffy. Beat in eggs and vanilla.
Whisk all remaining cookie ingredients in large bowl. Beat into butter mixture at low speed just until blended. Shape into flat round; refrigerate 30 minute.
Heat oven to 375°F Divide dough into 4 pieces. On lightly floured surface roll out each piece into 1/8" thick round. With 3" leaf shaped cookie cutter, cut out leaf shapes. Repeat with remaining dough. Reroll scraps (refrigerate dough if it gets soft). Place on baking sheet; bake 7 to 9 min or until light golden brown around edges. Cool on wire rock.
Meanwhile, beat 1 cup butter, maple syrup and maple extract in medium bowl at medium speed until smooth. At low speed, beat in 3 cups of the powdered sugar adding additional sugar if necessary to achieve spreadable consistency. Spread half of cookies with about 1 tbsp frosting; top with remaining cookies.