Preheat the oven to 425 degrees F and line a baking sheet with parchment paper or a baking mat.

In a large bowl, combine the flour, sugar, baking powder, and salt. Whisk together to combine well.

Use a cheese grater to grate the butter into the flour mixture. Then use a pastry cutter or a fork to combine the butter and flour mixture well (you can use a fork for the whole process but using a cheese grater first works super well - I recommend it). The goal is to have pea-sized pieces of butter mixed into your flour mixture.

Make a well in the center of the flour mixture and add the egg and buttermilk. Use a fork to whisk the two together and slowly bring in the flour mixture.

Stir until the biscuits just come together, taking care not to over mix.

Turn the dough onto a lightly floured surface and finish combining by lightly kneading the dough together.

Roll the dough into a 2-inch-thick slab. Use a  biscuit cutter to cut out as many biscuits as you can and place them on the prepared sheet, 1 inch apart.

Re-roll the dough and cut more biscuits until you have used all of the dough, adding a bit of flour to your work surface and rolling pin as needed. You should end up with 9-12 biscuits.

Bake the biscuits for 15-18 minutes until the tops are very golden brown.

Remove from the oven and serve right away.