To prepare pudding, combine raisins and 2 tablespoons bourbon in a bowl. Let stand 30 minutes. Drain mixture in a sieve over a bowl, reserving liquid.
Combine reserved liquid, milk, and next 6 ingredients (milk through eggs) in a large bowl, stirring well with a whisk. Add bread, tossing gently to coat. Spoon mixture into an 8-inch square baking dish coated with cooking spray. Sprinkle evenly with raisins, pressing gently into bread mixture. Cover with foil; chill 30 minutes or up to 4 hours.
Preheat oven to 350°.
Place dish in a 13 x 9-inch baking pan; add hot water to pan to a depth of 1 inch. Bake, covered, at 350° for 20 minutes. Uncover and bake an additional 10 minutes or until a knife inserted in center comes out clean.
To prepare sauce, combine 1/2 cup sugar, corn syrup, and butter in a small saucepan over medium heat. Bring to a simmer; cook 1 minute, stirring constantly. Remove from heat; stir in 1/4 cup bourbon. Serve each bread pudding piece warm with about 1 tablespoon sauce.