Heat vegetable oil in a deep fryer or large pot to 350°F. Meanwhile, prepare the dough.

In a medium bowl, whisk together flour, baking powder, and salt.

In a separate bowl, whisk together buttermilk and melted butter. Pour into dry ingredients and stir until just combined.

Turn dough out onto a floured surface and lightly knead. Roll out to about 1/2 inch thickness.

Cut into shapes using a donut cutter or a round cookie cutter with a smaller center cutout.

Carefully place donuts in hot oil and fry until golden brown, about 2-3 minutes per side.

Remove donuts from oil and drain on paper towels. Coat with sugar while warm.