Preheat oven to 450 degrees F.
In a large mixing bowl, whisk together flour, baking powder, sugar, and salt.
Melt butter in a microwave-safe dish 30 seconds at a time just until melted, being careful not to brown or burn the butter.
Once melted, pour butter into an 8" x 8" baking dish.
Pour buttermilk into mixing bowl with dry ingredients and stir to fully combine, but do not over mix.
Once combined, pour biscuit batter into the baking dish with the butter. Using the back of a spoon, gently spread the batter edge to edge in the dish. The melted butter will spill over the top of the batter.
Use a butter knife or sharp tool to cut the batter into 9 equal squares.
Bake in the oven for 20 - 25 minutes, or until the tops of the biscuits are nice and golden brown.
Let cool slightly before serving. These make a mean bacon, egg and cheese!