Preheat your oven to 350°F (175°C). Grease an 8x8-inch baking pan and line the bottom with parchment paper, allowing some overhang for easy removal later.
In a large mixing bowl, whisk together the pumpkin puree, granulated sugar, brown sugar, and vegetable oil until smooth. Add in the eggs and vanilla extract, mixing until combined.
In a separate bowl, sift together the flour, baking powder, baking soda, pumpkin pie spice, and salt. Gradually fold the dry ingredients into the wet mixture until just combined. Be careful not to overmix.
Pour the pumpkin batter into the prepared baking pan and smooth the top. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Allow it to cool completely in the pan.
In a medium saucepan over medium heat, combine the sugar and butter. Stir continuously until the sugar has melted and the mixture is bubbly. Gradually whisk in the heavy cream, being careful of splatter. Cook for an additional 4-5 minutes until the caramel thickens slightly. Remove from heat and stir in vanilla and a pinch of salt.
Once the pumpkin layer is cool, pour the caramel sauce over the top, spreading it evenly. If desired, sprinkle the chopped pecans and mini chocolate chips over the caramel layer.
Place the assembled bars in the refrigerator for at least 2 hours to allow the caramel to set. Once set, use the parchment overhang to lift the bars out of the pan and cut them into squares.
Serve chilled or at room temperature, and enjoy the delightful blend of pumpkin and caramel flavors.
Notes
Optional toppings include chopped pecans and mini chocolate chips.