Preheat oven to 350 degrees.
Use a hand mixer or stand mixer to cream the butter, brown sugar, and ½ cup granulated sugar together until light and fluffy.
Blend in the beaten egg and vanilla until thoroughly combined.
In a separate bowl, whisk together the baking soda, cream of tartar, salt and all-purpose flour.
Slowly add the flour mixture to the creamed mixture and blend until a soft dough forms and the ingredients are completely blended.
Remove ¼ cup of the dough to a small bowl and add a few drops of green gel color. Mix well.
Add a few drops of orange gel color to the large bowl and mix until well combined and no streaks remain.
Scoop the orange dough out by the tablespoonful (or use a small scoop) and roll into balls approximately the size of a golf ball. Roll each ball into the remaining granulated sugar to coat.
Place the orange sugared balls onto baking sheets lined with parchment paper (optional), and use a glass with a flat bottom (or a measuring cup) to flatten each ball into a disc.
Press a small dimple into the top of each pumpkin (where the stem will go), and use a paring knife to carefully cut four rounded slits onto each pumpkin.
Use the green dough to form a small cone shape for each pumpkin and press the narrow end into the area at the top of each pumpkin for the stem.
Use the paring knife to carefully cut two small slits on each pumpkin stem (optional).
Bake in a preheated oven for 18 minutes (or until the bottoms of the cookies are lightly browned, but not dark).
Cool the cookies on a wire rack and repeat the same process with the remaining dough.