In a medium-sized saucepan, add butter, heavy cream, granulated sugar, brown sugar, salt, and cinnamon. Stirring continuously, bring mixture to a boil until the temperature reaches 235 degrees F.
Remove pan from heat and add vanilla, do not stir mixture.
Allow mixture to cool to about 105 degrees F, or for about 30 minutes.
Vigorously stir the mixture for 1-2 minutes until it thickens. Add powdered sugar and pecans and continue stirring until the mixture loses its shine.
Spoon fudge onto a sheet of parchment paper and roll into log shape.
Refrigerate fudge for 1-2 hours or until firm.
Slice and serve chilled.
