Preheat your oven to 350°F (175°C).
Grease a 9x13-inch baking pan or line it with parchment paper.
In a medium bowl, whisk together the gluten-free flour, baking powder, baking soda, salt, cinnamon, nutmeg, ginger, and cloves.
In a large mixing bowl, combine the granulated sugar, brown sugar, and vegetable oil. Mix until well combined. Add the pumpkin puree, eggs, and vanilla extract, and beat until smooth.
Gradually add the dry ingredients to the wet mixture and stir gently until just combined.
Pour the batter into the prepared baking pan and spread it evenly.
Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Allow the bars to cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely before cutting into squares.