Use a glass baking dish to freeze the mixture; a metal pan can give the slush an off flavor. If you'd like a spicier slush, leave the seeds in the jalapeño and dip the rims of the glasses in water, then in ancho chile powder.
Bring pineapple juice to a boil. Add jalapeño pepper; cover, reduce heat, and simmer 5 minutes. Strain pineapple mixture through a sieve into a bowl; discard solids. Let cool 25 minutes.
Place strained pineapple juice, pineapple chunks, and next 5 ingredients (through milk) in a blender; process until smooth.
Pour mixture into an 8-inch square glass or ceramic baking dish. Cover and freeze 3 hours or until mixture is slushy, removing from freezer and scraping entire mixture with a fork every 30 minutes.
Spoon pineapple mixture into 4 glasses. Serve immediately.
Cooking Light Chill