Preheat the oven: Preheat your oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan.
Mix dry ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon until well combined. Set aside.
Mix wet ingredients: In a large mixing bowl, combine the pumpkin puree, sugar, and honey. Stir in the eggs and vegetable oil until smooth.
Combine mixtures: Gradually add the dry mixture to the wet mixture, stirring gently until just combined. Be careful not to overmix!
Pour batter: Pour half of the batter into the prepared baking pan. If desired, sprinkle with cinnamon and sugar for extra sweetness.
Add remaining batter: Pour the remaining batter on top of the first layer and gently swirl with a knife to create a marbled effect.
Bake: Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Cool: Allow the cake to cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.