In a shallow dish, stir together dried fruit and whiskey; set aside to soak for 30 minutes. In a small bowl, stir together brown sugar and pumpkin pie spice.
Preheat the broiler to high. Arrange croissants cut side up about 4" from broiler. Broil until lightly toasted. Spread butter over cut side of each croissant, dividing evenly.
Lightly butter an 11 x 7" baking dish; arrange 4 croissants butter side down in dish. Drain fruit, reserving whiskey. Sprinkle fruit and half of the sugar mixture evenly over croissants in dish. Arrange remaining croissants butter side up on top of fruit; sprinkle with remaining sugar mixture.
In a 4 cup measuring cup, whisk together milk, eggs, vanilla and reserved whiskey until well combined. Strain through a sieve into baking dish, drizzling evenly over croissants. Let stand for 30 minutes, occasionally pressing down on criossants to ensure they're well soaked.
Preheat the oven to 350.
Bake uncovered for 40 to 50 minutes until puffy, golden brown and crips. Let stand for about 5 minutes before serving.