Sift the flour into a mixing bowl. Using a box grater, grate the frozen butter into the bowl.
Using your hands, gently mix the butter with the flour. Make a well in the center of the mixing bowl and add the buttermilk. Mix everything together.
Lightly flour a kitchen surface. Transfer the dough onto it. Gently knead it several times, then roll it flat. Knead and roll out several more times.
Using a biscuit cutter or large cookie cutter, push down in the dough and shape the biscuits.
Generously grease an air fryer basket. Add 4 biscuits to it, ensuring the sides are lightly touching.
Air fry the biscuits for 9-10 minutes, or until golden.
Remove the biscuits from the air fryer and repeat the process with the remaining biscuit dough.
Notes
TO STORE: Pack them in airtight containers to store at room temperature for up to 3 days. If you'd like them to keep longer, store them in the refrigerator for up to one week. TO FREEZE: Place the cooked and cooled biscuits in a ziplock bag and store them in the freezer for up to 6 months.