Place pecans in a shallow baking pan in a 250° oven for 10 minutes or until warmed.
Grease a 15x10x1-in. baking pan with 1 tablespoon butter; set aside.
Grease the sides of a large heavy saucepan with the remaining 1 tablespoon of butter. Add sugar, water, salt and cinnamon and cook over low heat, stirring frequently until sugar is dissolved.
Turn heat to medium heat until mixture comes to a boil. Cover and cook for 2 minutes to dissolve all sugar crystals.
Continue to cook (without stirring) until a candy thermometer reads 236° (soft-ball stage). Remove pan from the heat and add vanilla. Stir in warm pecans until evenly coated.
Spread pecans onto the prepared baking pan. Bake at 250° for 30 minutes, stirring every 10 minutes. Remove and spread pecans onto a waxed paper-lined baking sheet to cool.