Preheat the oven to 350°F (180°C). Rub butter along the sides and bottom of the loaf pan. Add flour to the pan and rotate it around to coat the sides and bottom. Line the pan with parchment paper and use clips to hold the paper in place. The parchment paper is used as a sling to lift the quick bread out of the pan when it’s done.
Melt the butter in a small saucepan over low heat to prevent splatter and reduce evaporation. Remove the butter from the heat and set it aside. Let it cool to about 85°F degrees.
Put the flour, salt, baking soda, and baking powder in a medium-sized bowl. Whisk for 30 seconds to combine. Add the chocolate chips and toss the chocolate until they're well coated by the flour mixture.
Place the granulated sugar, brown sugar, and pumpkin pie spice in a large bowl. Use a whisk to combine. Use your fingers to break up any brown sugar clumps.
Add the eggs and whisk until thoroughly combined. Add the melted butter, whisk until incorporated, and then add pumpkin puree and whisk to combine. Add the buttermilk and whisk until thoroughly incorporated. Let the batter sit for 10 minutes to allow the sugar to dissolve further.
Add half the flour mixture to the wet ingredients and mix with a silicone spatula until the dry ingredients are mixed in. Add the remaining flour mixture and fold it into the batter until no white bits of flour are visible. There may be a few lumps and that is okay. Do not overmix.
Pour the batter into a loaf pan and use an offset spatula to spread the batter evenly across the pan.
Bake for 60-70 minutes or until a long skewer inserted in the center comes out clean with no more than a few crumbs clinging to it or the center registers at 195-200°F (90-93°C).
Rotate the pan after the first 30 minutes of baking.
Remove from the oven and allow to cool in the loaf pan for 10 minutes on a wire rack. Run a butter knife along the edges of the bread that are next to the loaf pan. Lift the bread from the pan and place it back on the cooling rack. Allow the bread to cool for 1 hour before slicing.