I served this at a pot luck with ginger snaps and graham crackers (when I wasn't heaping gobs of it into a cup and eating it with a spoon). You can use fancier cookies if you want, but these worked just fine. Lorna Doones would probably be tasty (but they never stick around long enough in my house to be dipped into anything).
15 ounce can pumpkin (NOT pumpkin pie filling)
5 ounce package instant vanilla pudding mix
1½ teaspoons pumpkin pie spice (or more, to taste)
16 ounces Cool Whip, thawed
In a large mixing bowl, beat pumpkin, pudding mix, and spices on low speed (or by hand) until thoroughly blended. Add Cool Whip, gradually increasing mixer speed. Beat on medium-high for about 1 minute or until evenly mixed and fluffy. Fold into serving bowl and refrigerate for at least one hour before serving.
This recipe makes about 6 cups of dip. If you want, you can divide this and freeze half for up to a month: put into a lidded freezable container, cover with plastic wrap (make sure the plastic touches the top of the dip to make a good seal when you cover), and then cover with the lid. Otherwise, this keeps for about 5 days (unless you eat it right ... oh never mind).
(No pictures, because we have access to plenty of spoons at work.)