Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan with butter or non-stick spray, then set it aside.
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, ground cinnamon, and ground nutmeg. Set aside.
In a large bowl, whisk together the canned pumpkin puree, granulated sugar, brown sugar, vegetable oil, eggs, and vanilla extract until smooth and well combined.
Gradually add the dry ingredients to the wet ingredients, folding gently with a spatula until just combined. Avoid overmixing to keep the bread tender.
In a separate small bowl, mix the softened butter and maple syrup together until creamy and well blended.
Pour half of the pumpkin bread batter into the prepared loaf pan. Dollop half of the maple butter mixture over the batter. Pour the remaining batter over that, then add the rest of the maple butter on top. Using a knife or skewer, gently swirl the maple butter into the batter to create a marbled effect.
Bake in the preheated oven for 55-65 minutes or until a toothpick inserted into the center comes out clean or with just a few moist crumbs. If the top begins to brown too quickly, tent it loosely with foil.
Allow the bread to cool in the pan for 10-15 minutes, then transfer it to a cooling rack to cool completely before slicing.