Preheat the oven to 350 degrees F and line a pullman pan or 9x5 loaf pan with parchment paper.

In a large bowl, whisk together the flour, baking powder, baking soda, salt, and pumpkin pie spice. Set aside.

Brown the butter: In a small saucepan, add 297g (21 tbsp) of unsalted butter and place over medium heat. As the butter melts, stir it with a rubber spatula to encourage even cooking. Once the butter has fully melted, it will alternate between rapid large bubbles and gentle small foamy bubbles. The butter will be ready once it turns a dark golden color and the fat solids have darkened and settled at the bottom of the pan. Immediately pour into a large bowl, scraping out the fat solids at the bottom, and weigh out to 227g (1 cup). Pour the remainder into a small bowl, and place in the fridge to solidify.

To the brown butter, whisk in the sugars, then the eggs and vanilla until fully combined. Then, whisk in the pumpkin purée.

Add the dry ingredients to the wet ingredients and gently mix until fully combined.

Pour the batter into the prepared pan and smooth out the top.

Transfer the remaining solidified brown butter to a piping bag and snip the end off. Use a knife to draw a straight line down the center of the batter. Pipe the brown butter along the line. Sprinkle pumpkin seeds on top, if desired.

Bake the pumpkin bread for 1 hour to 1 hour 10 minutes or until a deeply golden and a toothpick inserted comes out clean.

Allow the pumpkin bread to cool completely in the pan.

Use a serrated knife to cut individual slices and enjoy!