01 - Preheat the oven to 425°F. Line a baking sheet with parchment paper.
02 - In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly distributed.
03 - Add cubed cold butter to the flour mixture, using a pastry cutter or fork to blend until the mixture forms coarse, pea-sized crumbs.
04 - Pour in cold buttermilk and gently mix only until the dough begins to come together, taking care not to overmix.
05 - Turn out the dough onto a lightly floured surface and pat into a rectangle approximately 1/2-inch thick.
06 - Mix Flamin Hot seasoning, smoked paprika, cayenne pepper, and garlic powder in a small bowl. Sprinkle half the seasoning blend over the dough, fold the dough in half, and gently roll out again. Add the remaining seasoning, fold once more.
07 - Roll dough to a 1/2-inch thickness. Using a sharp knife or pastry cutter, slice into 24 strips, each about 5 inches in length. Twist each strip gently to form biscuit sticks and arrange them on the prepared baking sheet.
08 - In a large saucepan, bring water to a boil. Add baking soda. Working in batches, dip each biscuit stick into the solution for 10 seconds and return to the lined baking tray.
09 - Brush each stick with the beaten egg. Sprinkle with Parmesan cheese if desired and finish with a dusting of flaky sea salt.
10 - Bake for 16 to 18 minutes, or until the sticks are golden brown and crisp.
11 - Allow sticks to cool slightly before serving.