Heat the oven to 350°F and line baking sheets with parchment paper.
Stir the vanilla cake mix and pumpkin pie spice together in a large bowl.
Add the pumpkin puree and mix until no dry streaks remain.
Fold in the chopped pecans until evenly distributed.
Drop rounded tablespoons of dough onto the prepared sheets, leaving about 2 inches between cookies.
Bake for 10 to 12 minutes, cool on the sheets for 5 minutes, then transfer to a rack and cool completely.
Spread vanilla frosting over the cooled cookies before serving.