1-Preheat oven to 425°F.

2-If butter is fully frozen, let it thaw briefly for 5-10 minutes.

3-In a large bowl, whisk together the flour, baking powder, baking soda, salt, and garlic powder.

4-Grate the cold butter into the flour mixture using the largest holes of a box grater.

5-Toss the butter shreds into the flour with your fingers until coated.

6-Gently toss in the shredded cheddar cheese and scallions.

7-Add ¾ cup buttermilk and stir gently with a wooden spoon or spatula until the dough begins to come together.

8-Add remaining ¼ cup buttermilk if needed to moisten any dry spots. The dough should be cohesive but not sticky.

9-Turn dough onto a floured surface and gently pat it into a ½-inch thick rectangle.

10-Fold the bottom third of the dough up and the top third down over it, like folding a letter.

11-Pat the folded dough again into a ½-inch thick rectangle and fold once more.

12-Pat the folded dough out to a 1-inch thickness.

13-Using a floured biscuit cutter, cut the dough into rounds without twisting the cutter.

14-Gather scraps, gently pat together, and repeat cutting.

15-Place biscuit rounds close together on a baking sheet or cast-iron skillet.

16-Brush tops with the beaten egg wash.

17-Bake for 13-15 minutes, or until golden brown on top.