In a heavy saucepan, combine the sugars and cream; bring to a boil stirring often with a wooden spoon, or other heat-resistant utensil. Make sure all the sugar is dissolved. You want to bring the mixture to the soft ball point. Then, stirring often, add the butter, salt and pecans and bring the entire mixture to the hardball stage. With your spoon, drop small balls of the sugar and nut mixture onto a non-stick surface or parchment paper. They will flatten and spread as they cool.
For those unfamiliar with candy making: the softball point is about 236 degrees, the hardball point is about 245 degrees.