In a large bowl, mix together cake mix, pumpkin puree, egg, oil, and pumpkin pie spice until just combined. Dough will be very sticky. Fold in white chocolate chips.
Freeze the dough 10-15 minutes so it can firm up a bit and will be easier to handle.
Preheat oven to 350 degrees and line a baking sheet with parchment paper. If using, stir together sugar and cinnamon in a small bowl.
Scoop about 2 tablespoon of dough out at a time (I like to use a #40 cookie scoop) and drop directly into the cinnamon sugar mixture if using. Roll to coat.
Place dough on the prepared baking sheet and bake for 11-13 minutes, until set at the edges. Cool cookies for a few minutes before moving to a baking rack to cool completely.