In a large bowl, beat sugar, milk, buttermilk and melted butter until smooth.
In a medium bowl, mix together flour, baking powder and salt. Add to the wet ingredients and mix until just combined (dough will be sticky).
In a deep skillet, heat 1 inch of oil to 350°F. Using a small cookie scoop, scoop out a heaping scoop of dough. Drop, a few scoops at a time, into the oil and fry until golden brown (3-5 minutes on each side). Place dough balls onto a paper towel-lined plate.
While warm, roll bonuts into cinnamon sugar or into glaze. Serve warm.
