Place an oven rack in the center position and preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan with a thin layer of unsalted butter, or line it with parchment paper and leave a few inches of overhang on the two long sides.
In a medium mixing bowl, add 1 ¾ cups all-purpose flour, 1 teaspoon baking soda, and ½ teaspoon sea salt. Whisk for about 30 seconds until evenly distributed, then set aside.
In a large mixing bowl, beat ½ cup softened unsalted butter and 1 cup brown sugar with an electric mixer on medium speed for 2 to 3 minutes until creamy and slightly pale. Scrape down the sides of the bowl as needed.
Add 2 organic eggs one at a time, beating well after each addition. Pour in ¼ cup bourbon whiskey and ½ cup buttermilk, then mix until smooth and well combined. The batter may look slightly curdled, which is normal.
Add the flour mixture to the wet ingredients slowly, about one third at a time, stirring gently with a spatula or mixing on low speed after each addition. Mix just until no flour streaks remain; do not overmix.
Add 1 cup chopped pecans to the batter, setting aside a small handful for topping if desired. Fold gently with a spatula until the pecans are evenly distributed.
Pour the batter into the prepared loaf pan and smooth the top with a spatula. Sprinkle reserved pecans over the top if using. Bake for 50 to 60 minutes, starting to check at 50 minutes, until a toothpick inserted into the center comes out clean or with just a few moist crumbs.
Let the bread cool in the loaf pan for about 10 minutes, then lift it out using the parchment overhang or run a thin knife around the edges and turn it out onto a wire cooling rack. Cool completely before slicing with a serrated knife.