2 1/3 cups all-purpose flour, plus more for dusting
1 tablespoon sugar
1 teaspoon baking powder
1/2 teaspoon baking soda
1 teaspoon garlic salt
1/2 teaspoon freshly ground black pepper
4 tablespoons unsalted butter, softened
1 cup shredded Cheddar cheese
1/2 cup shredded Parmesan cheese
1 cup buttermilk
4 tablespoons unsalted butter, melted
2 teaspoons garlic salt
1 teaspoon dried parsley
2 tablespoons chopped fresh chives
To make the biscuits: Preheat the oven to 400°F. Prepare a baking sheet lined with parchment paper.
In a large mixing bowl, combine the flour, sugar, baking powder, baking soda, garlic salt, and pepper. Stir the ingredients to evenly combine. Add the softened butter, and work it into the dry ingredients until the butter becomes mealy in the flour. Add both cheeses and the buttermilk and work the ingredients together to create a sticky dough.
Lightly flour the work surface and roll the dough out to a 1-inch-thick rectangle. Cut the dough into thirds and stack them evenly on top of each other. Using a 3-inch cutter, cut the biscuits out of the dough and place them on the prepared baking sheet about 2 inches apart.
Bake until the biscuits are golden brown, 10 to 12 minutes.
To make the topping: In a small bowl, stir together the melted butter, garlic salt, and dried parsley. Allow the biscuits to cool for about 6 minutes, then brush with the melted garlic butter and sprinkle with the chopped chives.
Store leftovers in an airtight container at room temperature for up to 3 days.