1. Cream the butter and brown sugar in a medium bowl with an electric mixer on low until smooth; stir in the egg yolk. Mix the flour, pumpkin-pie spice and baking soda in a large bowl. Stir in the butter mixture. Mix until the dough is firm and smooth. Form the dough into a disk; wrap in plastic wrap and chill for 20 minutes.
2. Preheat the oven to 375°F. Line cookie sheets with parchment paper or leave ungreased.
3. Roll the dough to a 1/4-inch thickness on a lightly floured surface. Cut out cookies with a 3 1/2-inch round cookie cutter and place 2 inches apart on prepared baking sheets. Bake until lightly browned around the edges, 10 to 12 minutes. Remove from oven and transfer cookies to wire racks; cool completely.
4. Create faces on pumpkin cookies using the orange icing.
Variation
For whole-wheat cookies, substitute 2 1/2 cups whole-wheat flour for the all-purpose flour and use a whole egg instead of just the egg yolk.
Cookie Cutter Tip
If a 3 1/2-inch round cookie cutter is not available, a clean wide-mouth glass jar works well, too.