Preheat the oven to 350°F and grease a 9"x5" loaf pan with cooking spray.

In a medium bowl, whisk together flour, baking soda, cinnamon, pumpkin pie spice, baking powder, and salt.

In a large bowl, whisk together eggs, pumpkin puree, granulated sugar, oil, buttermilk, and vanilla until smooth. Add dry ingredients and fold with a rubber spatula until just combined.

Transfer 1 cup of batter to a small bowl and stir in Nutella.

Using an ice cream scoop or measuring cup, place about 1/4 cup of pumpkin batter in one corner of the prepared pan. Place about 1/4 cup of Nutella batter directly next to it. Repeat alternating scoops of batter to cover the bottom of the pan in a checkerboard pattern. Repeat with the remaining batter to form a second layer.

Place the end of a chopstick or skewer into the batter and drag back and forth across the batter. Rotate the pan 90° and drag back and forth across the batter again.

Bake the bread until a tester inserted into the center comes out clean, about 60 to 65 minutes.

Let the bread cool for 15 minutes, then carefully remove it from the pan, transfer it to a wire rack, and let it cool completely. Enjoy your delicious marbled pumpkin bread!