Preheat oven to 350ºF.

Combine dry ingredients in a small mixing bowl, and set aside.

In a large mixing bowl, beat butter and sugars together until fluffy.

Beat in egg, then add vanilla and pumpkin purée, beating until fully incorporated between each addition.

Stir in flour mixture until fully mixed.

Drop cookie dough by the tablespoon onto a parchment-lined baking sheet.

Bake in center of the oven for 10 minutes until just done. Firm but not brown.

Remove from oven and immediately press a 'thumbprint' into the center of each cookie using the back of a spoon. Let cool completely before icing.

While the cookies cool, combine cream cheese icing ingredients and beat together until smooth.

Once cookies are completely cooled, fill each with icing using a piping bag with a star tip.

Sprinkle any add-on toppings on while the icing is still moist.