Combine all ingredients except for butter, vanilla and pecans in a heavy saucepan over medium heat. Bring to a boil, stirring until the sugars dissolve. Cook until the soft ball stage. Remove from heat.
Prepare an area to spoon the candy out onto. I use wax paper but you could also use parchment paper. TIP: I have found that if you let the candy mixture cool some first then you don't have to beat it as long
Add butter, vanilla and pecans to saucepan. Beat until it starts to thicken and loses some of its gloss. Spoon out quickly onto prepared countertop in the size you prefer. Store in a covered container.