Preheat oven to 425°F (218°C). Line a baking sheet with parchment paper and set aside. 

In a large bowl, whisk together the flour, baking powder, sugar, and salt. 

Slice the cold butter into cubes and cut the butter into the flour mixture using a pastry blender until the flour mixture is full of pea-sized chunks of butter. 

Add about a third of the buttermilk buttermilk and gently stir until blended. Add another third of the buttermilk and gently stir until blended. Add the rest of the buttermilk and gently stir just until the buttermilk is fully incorporated and there is no dry flour. Be careful not to overwork the dough when mixing. When all of the buttermilk is added, the dough will be a bit wet and sticky.

Place the dough onto a generously floured surface and knead the dough gently a few times. Sprinkle a bit of flour over the dough and knead the flour into the dough if the dough is too wet and sticky to work with.

Using a rolling pin, gently roll the dough to ½ inch (about 1.25 cm) thickness.

Dip the edges of a 2 ½ inch (about 6.5 cm) circle cutter in flour, then use it to cut the dough into circles. (Tip: Press the cutter straight down and lift it straight up to cut the dough, rather than twisting the cutter in the dough. Twisting the cutter can seal the edges of the dough and limit the biscuits' rise.) Re-roll the remaining dough to cut additional biscuits.

Place the biscuit dough circles onto the parchment-lined baking sheet. Bake until the edges are slightly golden, about 15 minutes.

Place the baking sheet onto a wire rack, leaving the biscuits on the baking sheet to cool slightly. Serve the biscuits warm with the toppings of your choice or allow them to cool completely before storing.