Place soft butter and vanilla in a medium-size mixing bowl. Stir with a wooden spoon or sturdy spatula until nice and smooth. Add powdered sugar. Mix together until fluffy and well blended.
Sprinkle the flour and cornstarch evenly over the top. Stir until flour is incorporated and the dough is shaggy. Turn out onto a well-floured surface and form it into a ball. Knead the dough a few times on the well-floured surface until fairly smooth then form into a ball again and press with your hands into a flat disk.
On a floured work surface, roll out dough to a 3/8-inch thickness. Keep work surface, dough and rolling pin dusted with flour.
Using a pumpkin-shaped cookie cutter cut into shapes and place on prepared pans. Re-roll scraps as many times as needed to use up the dough.
Place cutouts in the refrigerator for at least one hour or up to 24 hours.
When ready to bake, preheat oven to 350˚F. Remove cookies from the refrigerator and bake for 12-16 minutes or until light golden brown. Rotate pans halfway through, if needed, for even browning. Cool completely before icing.
Combine powdered sugar, half and half and vanilla extract in a medium-size bowl. Mix until smooth. The glaze should be thick, but pourable. Add a little more half and half if it's too thick.
Dip the tip of a small knife into the orange food coloring and swirl some of it into the icing. Stir well and add more food color until the desired shade of orange is achieved. Transfer the glaze to a shallow bowl.
Holding onto the edges of a cookie, dip the top surface into the glaze, being sure all of the surface touches the glaze. Pull the cookie up and out of the glaze. Allow excess glaze to drip back into a separate bowl. When the glaze stops dripping (this will take a while, quickly flip the cookie right side up and give it a gentle jiggle to allow the glaze to flow evenly over the surface. See the picture above in the post.
After each cookie is glazed and still wet, immediately add the green sprinkles for the stem and leaves with a small spoon. See the picture above in the post.
See Café Tips above for lots of extra tips and instructions.
The recipe makes 15 large (3-inch) or two dozen smaller (2-inch) cookies.
Once cookies are dry, they can be stacked in an airtight container.