Preheat the oven to 350F; line a 9 by 5-inch loaf pan with 2 pieces of parchment paper so it hangs over all 4 sides. Lightly spray the inside (especially the corners) with coconut oil spray.
While it’s still hot, carefully beat together the browned butter with the avocado oil and sugar until well combined. Beat in the eggs, and then the molasses, vanilla, and pumpkin.
Sift in the flour, baking soda, salt, cinnamon, ginger, nutmeg, cloves, allspice, cardamom, and black pepper, and stir just to combine, being careful not to over-mix. Fold in the walnuts or pecans (if using).
Pour the batter into the prepared pan and bake until a wooden pick inserted in the center comes out clean, about 65 to 80 minutes.
Cool completely before slicing.
Notes
Recipe Yield and Serving Size: This recipe makes 1 (9 by 5-inch) loaf or 18 servings. Each serving is 1 slice, about ½-inch thick.
Storage: Store homemade pumpkin bread wrapped at room temperature for up to 5 days. To keep it as fresh as possible, I like to wrap it in plastic wrap and then put it in a gallon-sized zip-top plastic bag.