01 - In a medium mixing bowl, whisk together all-purpose flour, baking soda, baking powder, salt, cinnamon, ginger, and nutmeg until evenly distributed.
02 - In a large bowl, use an electric mixer to beat softened butter, granulated sugar, and brown sugar until light and fluffy. Add the egg, pumpkin purée, and vanilla extract, mixing until fully incorporated.
03 - Gradually add the flour mixture to the pumpkin mixture, mixing at low speed until just combined. Avoid overmixing.
04 - Cover the bowl with plastic wrap and refrigerate the dough for at least 1 hour to firm up for easier shaping.
05 - Preheat oven to 350°F. Line two baking sheets with parchment paper for even baking and easy cleanup.
06 - On a lightly floured work surface, roll chilled dough to 1/4-inch thickness. Cut out cookies using a 2-inch round or pumpkin-shaped cutter. Reroll dough scraps as needed.
07 - Transfer shaped cookies to prepared baking sheets. Using a small paring knife, cut Jack-o'-Lantern faces into half of the cookies for sandwich tops.
08 - Bake cookies for 10 to 12 minutes until set but still soft. Cool completely on a wire rack to prevent melting.
09 - For each sandwich, place a scoop of slightly softened vanilla ice cream onto the flat side of a plain cookie. Gently press a cookie with a Jack-o'-Lantern face on top to form a sandwich.
10 - Arrange assembled sandwiches on a tray and freeze for at least 30 minutes to set the filling.
11 - Before serving, use black decorating gel or melted chocolate to accentuate the Jack-o'-Lantern features if desired.