• Preheat the oven to 350°F. Line baking sheets with parchment paper and set aside.

Make the cookie dough.

• In a medium bowl, whisk together the flour, cornstarch, baking soda, baking powder, salt, and spices. Set aside.
• In a the bowl of a stand mixer using the paddle attachment (or in a large bowl using an electric hand mixer), cream the butter and both sugars until light and fluffy.
• Add egg yolk and beat until well blended. Add pumpkin and vanilla and beat until well blended.
• Add the dry ingredients and stir using a wooden spoon or rubber spatula just until combined.

Bake the cookies.

• Scoop 1 ½ Tablespoon balls of cookie dough onto the prepared baking sheets at least 2 inches apart.
• Bake cookies one tray at a time for 12 minutes, or until cookies are puffed in the center with golden edges. Let cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.

Make the frosting.

• When the cookies have cooled, mix the cream cheese frosting. In the bowl of a stand mixer using the paddle attachment (or in a large bowl using an electric hand mixer), beat cream cheese and butter on high speed until smooth, about 1 minute. Add vanilla and salt and beat to combine.
• With the mixer running on low speed, slowly add confectioners’ sugar until all the sugar is added. Then beat on high speed until the mixture is well combined and creamy.

Decorate the cookies.

• Transfer ¼ cup of the frosting to another bowl, add a drop of green gel food coloring, and mix until the color is even. Add orange gel food coloring to the remaining frosting and mix until well blended. You may want to briefly chill the frosting before piping (see Notes).
• Add the green frosting to a piping bag fitted with a tiny round tip, and transfer the orange frosting to a piping bag fitted with a flat tip.
• Pipe orange frosting in a curved vertical stripe on each of a cookie's outer edges.
• Continue to pipe, working inwards, with two more curved stripes overlapping the first and then one straight stripe in the center to create a pumpkin shape.
• Pipe green frosting in short lines at the top of the cookie to create the pumpkin's stem, continuing with a little twist down one side to create a curly offshoot with leaves.
• Repeat with the other cookies until all are decorated.