Preheat oven to 450 °F.

In a large bowl, sift in flour, baking powder, baking soda, salt and mix them well with a spoon.

Grate the frozen butter and add it to the flour mixture.

Use your fingertips to incorporate the butter to the flour mixture, until the mixture resembles coarse crumbs.

 Add buttermilk and mix until just combined.

Flour a working board and place the dough on it.

Flatten the dough with hands or with a rolling pin. Shape a rectangle form and start folding the rectangle in half.

Repeat the operation of flattening and folding the dough for 4 to 5 times (the layering process helps form flaky biscuits). Make sure to lightly flour the dough before folding it.

Roll out dough to about ½ inch thick and cut it out into circles, using a cookie cutter(I have used a 2 inches diameter cookie cutter but the size is your choice). Make sure to dip the cookie cutter into flour to prevent it from sticking to the dough.

Place cut out biscuits dough on a baking sheet that are lined up with parchment paper.

 Brush the top of the biscuits with buttermilk.

 Bake for 10 minutes or until golden brown (rack placed in the center of the oven).

 Immediately brush biscuits with melted butter.