Place 2 cups sugar and milk in a large saucepan. Cook slowly, stirring often. At same time, put the 1 cup sugar in another saucepan on low heat; stir until melted. Pour slowly into the milk and sugar that should be ready to boil; stir while adding. Cook slowly until a firm ball will form when dropped into cold water (238 degrees F on a candy thermometer).
Set off the heat. Add vanilla extract, pecans and butter. Beat or stir until this begins to thicken. Drop by spoonsful on wax paper. They should set up immediately.
