Use a bit of butter to grease a baking sheet, preferably one with a low rim.
In a heavy skillet, over medium heat, combine sugar and 2 tablespoons water
Stir until smooth,; cook, adjusting heat so that mixture bubbles steadily.
Stir occasionally until mixture turns golden brown which it may do rather suddenly.
Stir in the peanuts and a large pinch of salt, if desired.
Pour mixture onto greased baking sheet and spread out.
Cool for about a half-hour, then break into pieces.
Can also be scored, with a knife, when it has solidified slightly but not yet turned hard; that way, it will break into even squares.
Store in a covered container for up to two weeks.