To prepare cookies, lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking soda, salt, and pie spice, stirring with a whisk. Place granulated sugar, butter, and brown sugar in a large bowl; beat with a mixer at medium speed until well blended. Add pumpkin, egg substitute, and vanilla; beat well. Gradually add flour mixture to sugar mixture, stirring just until moist.
Drop dough by level tablespoons 2 inches apart onto baking sheets coated with cooking spray. With moist hands, flatten cookies into 3-inch circles. Bake at 350° for 15 minutes or until set. Remove cookies from baking sheet; cool completely on wire racks.
To prepare filling, combine ice cream and syrup; cover and freeze 30 minutes or until firm. Spread about 1/4 cup ice cream onto the flat side of each of 15 cookies. Top with remaining cookies, flat sides down, pressing gently. Wrap each sandwich tightly in plastic wrap; freeze 4 hours or until firm.