Flaky Golden Brown Buttermilk Biscuits

Ingredients

• 3/4 teaspoon baking soda
• 1 and 1/4 teaspoons salt
• 2 and 1/3 cups (280 g) all-purpose flour (plus extra for hands and work surface )
• 1 and 1/2 cups (180 g) cake flour
• 2 Tablespoons (28 g) aluminum free baking powder
• 3/4 cup (170 g) unsalted butter (frozen and coarsely grated )
• 1 large egg (cold )
• 1 and 1/3 cups (303 ml) buttermilk (cold, plus more for brushing )
• 2 Tablespoons (43 ml) honey
• 4 Tablespoons (57 g) unsalted butter
• 1 and 1/2 teaspoons flaky sea salt