Preheat your oven to 350°F (175°C) and grease a 9-inch round cake pan or line it with parchment paper.
In a large mixing bowl, combine pumpkin puree, sugar, eggs, and oil. Whisk until the mixture is smooth and well combined.
In another bowl, sift together the flour, baking powder, cinnamon, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Be careful not to overmix.
In a small bowl, mix together ¼ cup sugar with 1 tsp cinnamon for the cinnamon swirl.
Pour half of the batter into the prepared pan. Sprinkle half of the cinnamon-sugar mixture over it. Add the remaining batter and top with the remaining cinnamon-sugar mixture.
Bake in the preheated oven for 25-30 minutes or until a toothpick comes out clean. Let cool in the pan for 10 minutes before transferring to a wire rack.
Enjoy warm or at room temperature, paired with a cup of coffee or tea!