01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, allowing for overhang to facilitate removal.
02 - Whisk together the flour, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, and cloves in a medium bowl.
03 - In a large bowl, whisk the pumpkin purée, light brown sugar, granulated sugar, vegetable oil, eggs, and vanilla extract until smooth and homogenous.
04 - Stir the dry mixture into the wet ingredients until just combined. Avoid overmixing for tender bars.
05 - Spread two-thirds of the batter evenly into the prepared pan.
06 - Drizzle thick caramel sauce over the batter. Use a knife or skewer to gently swirl caramel throughout.
07 - Dollop the remaining batter over the caramel swirls and gently spread to partially cover.
08 - Sprinkle with chopped pecans or walnuts if desired.
09 - Bake for 32 to 36 minutes, or until a toothpick inserted in the center exits with moist crumbs but no wet batter.
10 - Cool completely in the pan. Drizzle with additional caramel and sprinkle with flaky sea salt as desired. Cut into bars for serving.