Preheat your oven to 250 °F. Grease a large rimmed baking sheet with the extra butter and set aside.
Place the butter in a large heavy saucepan that is appropriate for candy making and add in add sugar, water, salt, and cinnamon. Place over medium high heat and bring to a rolling boil, stirring constantly.
Scrap any sugar crystals on the sides of the pan into the mixture.
Turn down the heat and keep the rolling boil, then to form the candy syrup, cook, WITHOUT STIRRING, until a candy thermometer reads between 235° F–240° F (soft-ball stage). See the directions in the post how to tell soft ball stage without a thermometer using the water method. For the BEST results, use the thermometer and the water method!
Once ready, remove the pan from the heat and stir in the vanilla.
Stir in the pecans until evenly coated.
Spread onto prepared baking pan, Bake at 250° for 30-35 minutes, stirring every 8-10 minutes.
Once baked, spread onto a waxed paper-lined baking sheet to cool. When spreading out to cool, separate with a fork so they don't clump together! You want them to cool separately.
Keep in an airtight container for up to two weeks, but they will not last that long.