Prep Line a baking sheet with parchment paper or a silicone mat. Set out a spoon or small scoop for later.
Cook sugars and milk. In a heavy saucepan, combine the granulated sugar, brown sugar, and evaporated milk. Cook over medium heat, stirring constantly, until the mixture reaches 228°F (thread stage).
Add butter and pecans, cook again. Add the butter and pecans. Continue cooking and stirring until the mixture reaches 236°F (soft-ball stage).
Stir. Remove from heat and stir in the vanilla. Continue stirring until the mixture thickens slightly and loses its glossy look.
Shape and cool. Quickly drop spoonfuls onto the prepared baking sheet. Let cool until firm.
Notes
Work quickly once the mixture thickens. It sets fast!