Preheat the oven to 425 degrees F and place rack in the center of oven. Line a baking sheet with parchment paper and set aside.
In large bowl, whisk to combine the flour, baking powder, 1 teaspoon of the pepper, the salt, sugar and baking soda. Cut the butter into the flour until combined, and then stir in 1 cup of the buttermilk, adding 1/4 cup more if needed, until a rough dough forms.
Turn the dough onto a work surface, knead gently to combine, and then pat into an 8-inch square. Cut into 9 square biscuits and place on the prepared baking sheet about 2 inches apart. Brush the tops with buttermilk and sprinkle the flaky salt and the remaining 1/2 teaspoon pepper over the tops. Bake until the tops are golden and the biscuits are fluffy and cooked through, 20 minutes.
Slather with Bacon Butter to serve.
In a skillet set over medium heat, cook the bacon until lightly crisp, 3 to 5 minutes per side. Drain on a paper-towel-lined plate and reserve 1 tablespoon of the bacon fat.
Place the bacon in a food processor with the butter and the reserved bacon fat. Add the pepper and salt. Pulse until well combined. Refrigerate until the butter firms up. Yield: 1/2 cup