Brown the butter: Cook 1/2 cup butter in a light saucepan over medium heat, stirring frequently, until it turns deep golden brown and smells nutty (about 5-7 minutes). Pour into a bowl and set aside to cool slightly.
Preheat your oven to 350°F. Grease a 9x5 inch loaf pan or line it with parchment paper, leaving an overhang on the two long sides.
In a medium bowl, whisk together the flour, baking soda, salt, cinnamon, nutmeg, ginger, and cloves. Set aside.
In a large bowl, whisk the slightly cooled browned butter with brown sugar and granulated sugar. Add the pumpkin puree and whisk until smooth. Add the eggs one at a time, whisking well after each. Whisk in the buttermilk and vanilla extract.
Add the dry ingredients to the wet in two additions, folding gently with a rubber spatula until just combined and no flour streaks remain. Do not overmix.
Pour the batter into the prepared loaf pan and smooth the top. Bake for 55-65 minutes, until a toothpick inserted in the center comes out clean or with a few moist crumbs.
Let the loaf cool in the pan for 15 minutes, then lift it out onto a wire cooling rack to cool completely before glazing.
For the glaze, brown 3 tablespoons of butter in a small saucepan. Whisk it with the sifted powdered sugar, maple syrup, and a pinch of sea salt. Add milk, a teaspoon at a time, until smooth and pourable.
Drizzle the glaze generously over the cooled loaf, letting it drip down the sides. Let the glaze set for about 10 minutes before slicing and serving.