Preheat the oven to 230°C. Line a baking tray with parchment paper or leave it unlined if it is light-colored and clean. A hot oven is important — biscuits need strong initial heat so the butter releases steam quickly and lifts the layers before the structure sets. That aggressive initial heat is precisely what converts the dough's carefully preserved cold fat pieces into steam fast enough to actually lift the layers — a cooler oven would let the dough's structure begin setting before that lift has a real chance to happen.

In a large bowl, whisk together the flour, baking powder, baking soda, salt, and sugar until evenly combined. Distributing the leaveners thoroughly matters — uneven mixing gives uneven lift. That thorough whisking ensures the baking powder and soda are dispersed consistently throughout the flour, rather than clumped in pockets that would cause some biscuits to rise more than others.

Add the cold butter. Work it into the flour using your fingertips, a pastry cutter, or by rubbing it lightly between your fingers until the mixture contains a mix of fine sandy crumbs, pea-sized butter pieces, and a few larger flat shards of butter. Do not fully blend the butter in. Those visible butter pieces are what create steam pockets and flaky layers in the oven. If the butter starts softening, place the bowl in the fridge for 5–10 minutes before continuing. That deliberate range of fat piece sizes — from fine crumbs up to larger flat shards — is what builds real textural variety into the finished biscuit, with the larger shards specifically responsible for the most dramatic, visible layers.

Pour in the cold buttermilk and mix gently with a fork or spatula just until a shaggy dough forms and no obvious dry flour remains. The dough should look rough, soft, and slightly sticky, not smooth. Do not knead it like bread dough. Overworking develops too much gluten and gives dense biscuits instead of tender ones. Stopping the mixing the moment the dough comes together, rather than continuing for a smoother appearance, is what protects the finished biscuits from toughening — flour's gluten develops more the longer it's worked, and this dough has genuinely little need for that extra structure.

Turn the dough out onto a lightly floured work surface. Pat it into a rough rectangle about 2.5cm thick. Fold it like a letter: fold one third inward, fold the other third over it. Turn the dough 90 degrees, pat it out again, and repeat this folding process 2 more times. This gives you 3 total fold rounds. These folds are what create the tall layered sides. Keep it gentle — you are stacking layers, not kneading. That repeated folding mechanically builds real, distinct, stacked layers into the dough before it ever reaches the oven — a single pat-out, without this lamination, simply wouldn't produce the same tall, visibly layered sides this biscuit depends on.

Pat the dough into a final rectangle about 3cm thick. Use a round cutter about 6–7cm wide and cut straight down without twisting. Twisting seals the edges and can reduce the rise. Gather the scraps gently, pat once more, and cut the remaining biscuits until you have 12 total. Arrange them on the tray: place them slightly apart for more defined edges, or place them just touching for softer sides and a taller upward rise. For classic Southern-style tall biscuits, placing them just touching works very well. Cutting straight down, never twisting, protects the dough's own cut edges from being sealed shut — a twisted cut would trap the layers built during lamination, directly limiting how much the biscuit can rise.

Place the tray in the fridge or freezer for 10 minutes. This re-firms the butter and helps the biscuits hold shape and rise taller instead of spreading. That brief chill firms the butter back up after all the handling during shaping, giving the biscuits real structural stability right before they meet the oven's aggressive initial heat.

Brush the tops lightly with buttermilk. Bake at 230°C for 15–18 minutes, until the tops are richly golden brown and the biscuits have risen high with clearly visible layers. The tops should be well colored, not pale. Pale biscuits are usually underbaked and tend to have a doughier center. That deep golden colour reflects real, substantial baking having taken place all the way through — a paler biscuit pulled too early would still taste doughy at its centre despite looking technically finished on top.

Remove from the oven and, if desired, brush lightly with melted butter for extra flavor and a soft sheen. Let rest for 5 minutes before serving. Serve warm. One biscuit split open with butter melting into the middle is the benchmark. Brushing that optional butter on while the biscuits are still genuinely hot lets it melt in and soak slightly into the surface, adding real richness rather than sitting as a separate, unabsorbed layer.