Preheat the oven to 180°C/356°F (without fan).
If you are using a traditional loaf pan, line the pan with some baking paper. If you are using a springform loaf pan, line the bottom with baking paper and grease the sides. For this recipe, I used a springform loaf pan measuring 11 x 30 x 8 cm (4 x 12 x 3 inches). Place the cooled brown butter and sugar into the bowl of a stand mixer.
Beat the butter and sugar together on medium speed for a few minutes, scraping down the sides as necessary.
Add the eggs, vanilla and pumpkin purée.
Beat together lightly until everything is loosely mixed together.
Measure the flour, baking soda, salt, cinnamon and nutmeg into a bowl.
Slowly add the dry ingredients to the wet ingredients, one tablespoon at a time.
Add most of the chocolate chips (reserve a small handful to decorate the cake) and stir this through the batter.
Pour the batter into the prepared loaf pan.
Use a small spatula to spread the batter evenly.
Sprinkle the reserved chocolate chips on top of the cake.
Bake the cake for 40-45 minutes, or until a skewer inserted in the centre of the cake comes out clean.
Cool the cake in the pan on a wire rack for about 10 minutes.
Carefully remove the cake from the pan, and remove the baking paper.
Allow the cake to cool on a wire rack, but you can also serve the cake warm.