Melt butter in a saucepan over medium heat; cook and stir pecans in melted butter until lightly toasted, 2 to 3 minutes. Transfer toasted pecans to a bowl with a slotted spoon, reserving butter in pan. Cook and stir apples in reserved butter until apples begin to soften, about 2 minutes; add sugar.
Stir water, raisins, and salt into apple mixture. Simmer, stirring occasionally, until raisins are plump, about 5 minutes. Add whiskey, vanilla extract, and toasted pecans.