Turn your oven on to 425 degrees. Cut your cube of butter into slices and place them in a 9x9" square baking dish.
Place the dish in the oven for a few minutes to melt the butter. Don't let it burn, it will only take a few minutes.
While the butter is melting, prepare the biscuit dough. Whisk together the flour, baking powder, sugar, and salt in a large mixing bowl.
Add the cold buttermilk and stir gently, just until barely mixed together.
Remove the pan of melted butter from the oven. Using an ice cream scoop or large spoon, drop 9 mounds of dough into the butter.
As soon as your oven is preheated to 425°, return the pan to the oven. Bake for about 30 minutes, or until golden brown on the top and bottom.
Notes
If you prefer, you can just melt the butter in the microwave.
For the best biscuits, use salted butter! Unsalted butter just doesn't add enough flavor.
Some recipes call for just spreading the dough on top of the butter, then trying to cut it into sections with a bench scraper, but I think the scooping method is much easier!
I don't recommend using unsalted butter for
I've never had a problem with the butter spilling out of the pan, but you can place a cookie sheet underneath if you are worried. Just keep in mind that the bottoms won't brown as well.