Cut butter into small cubes. Place the butter on a plate and place in the freezer while you mix the dry ingredients. The butter should be very cold.
Preheat oven to 450°F and line a baking sheet with parchment paper or nonstick foil. Set aside.
In a food processor (or large bowl), add flour, sugar, baking soda, baking powder and salt. Pulse a time or two to combine (or whisk if you're using a bowl).
Add the butter to the food processor and pulse to combine, until it looks like coarse crumbs (you could also use a pastry cutter or 2 forks in a large bowl).
Add the butter and flour mixture to a large bowl and make a well in the middle. Add the cold buttermilk. Stir until dough is mixed and combined, it will be slightly sticky/tacky. If it's still really sticky, add a bit more flour!
Turn out the dough onto a floured surface (I use my counter) and pat into a rectangle about 8-9 inches long.
Gently fold the right side towards the middle, then fold the left side in towards the middle as well. It should look like a trifold paper.
Rotate the dough a quarter turn (it should be horizontal), then pat down into a 8-9 inch long rectangle again. Repeat the folding technique from the step above, at least 1 more time, and up to 2 more times. So 2 or 3 times total. The more folding you do, the more layers you'll have.
Pat dough down into a rectangle again, about 1 inch thick.
With a 2.5 inch round biscuit cutter, push down to cut the dough and pull straight up (remember not to twist!). Leftover scraps can be combined and cut again – but no more than 2 or 3 more times.
Place the biscuits on prepared baking sheet, almost touching each other, and bake at 450°F for 12-15 minutes until browned and cooked through.
After the biscuits are baked, brush tops with melted butter.