1-First, preheat the oven to 400°F. Place 1 tablespoon of the cold unsalted butter in an 8×8-inch baking pan and melt it in the oven for 3-5 minutes, then brush it over the bottom and sides of the pan and set aside. Next, cut the remaining 10 tablespoons of cold unsalted butter into small pieces. In a large bowl, whisk together 3 cups all-purpose flour, ½ cup granulated sugar, 2 teaspoons baking powder, ½ teaspoon baking soda, and 1 ¼ teaspoons fine sea salt.

2-Then, add the butter pieces and work them into the flour mixture using your fingertips or a pastry blender until it resembles coarse meal. Gently toss in 1 ½ cups fresh blueberries to keep them intact. Stir in 1 ⅔ cups cold buttermilk until no dry flour pockets remain; the batter will be thick and sticky. Transfer the dough evenly to the prepared pan, spreading it into the corners, and lightly spray a bench scraper with nonstick spray to score the dough into 9 equal squares without separating.

3-Bake for 40-45 minutes, or until the tops are browned and a knife inserted into the center comes out clean. Cool the biscuits in the pan for 5 minutes, then turn them out onto a baking sheet, flip onto a wire rack, and prepare the honey butter by melting 2 tablespoons unsalted butter, 1 tablespoon honey, and a pinch of salt in the microwave for 30-60 seconds. Brush the tops with this mixture and cool for another 10 minutes before cutting along the scored lines with a serrated knife and serving warm.