With an electric mixer combine butter, brown sugar and sugar and beat until light and creamy. Add in egg and mix until combined. Add in vanilla and pumpkin and mix until well combined.
In a separate bowl combine flour, baking powder, baking soda, cornstarch, cinnamon, pumpkin pie spice and salt. Mix until well combined.
Combine wet and dry ingredients until just combined. Do not over mix. Add in caramel sauce and stir gently. You do not want to over mix or the caramel sauce will just absorb into the dough, you want more of a swirl of caramel sauce through your cookie dough.
Scoop your cookie dough using a cookie scoop onto baking sheets lined with a Silpat or parchment paper (don't skip this step!). Cookies should be about 2" apart from each other. Sprinkle the tops with sea salt. Bake for approximately 11-13 minutes. Remove from oven and allow to cool fully on baking sheet prior to removing. Repeat with remaining cookie batter.
Cookies are best when stored individually wrapped or in a container where they are not layered on top of each other.