Preheat the oven to 350 degrees Fahrenheit. Spray a 9x9 baking pan with cooking spray.
In a small bowl, combine arrowroot starch and water. Whisk to combine then set aside. In a separate small bowl place raisins and whiskey and set aside.
In a large bowl, combine almond milk, applesauce, coconut milk, vanilla extract, maple syrup, salt, cinnamon, and nutmeg. Whisk to combine. Add arrowroot starch mixture and whisk again to incorporate. Add the cubed bread to the mixture and then gently fold with a large spoon or rubber spatula until most of the bread is saturated.
Transfer the bread mixture and any remaining liquid to the prepared baking pan. Strain the raisins from the whiskey (save the whiskey) and sprinkle them over the top. If making vanilla sauce, the whiskey will be used there.
Brush the tops of the bread cubes with melted butter. Bake for 45 minutes to an hour, tenting with foil at the 30-minute mark (50-55 minutes was perfect for me). The result should be golden and slightly crisp on top and a bread pudding custard consistency on the bottom.
To Make Vanilla Sauce: In a small saucepan, add almond milk and arrowroot starch. Whisk until arrowroot is dissolved. Add the remaining ingredients and turn to medium-high heat, whisking often, for about 3 minutes. Lower heat for one minute and then remove from heat.
Serve bread pudding with a generous drizzle of vanilla sauce on top of each serving.
Notes
To reheat leftover bread pudding, cover the casserole dish with foil and warm it in a 350-degree Fahrenheit preheated oven for 10-15 minutes.
Stale bread or day-old bread over fresh bread is best for this recipe as it absorbs the liquid better. You can use homemade gluten-free bread or store-bought gluten-free bread.
Need to dry out your bread faster? Lay the cubed bread out on a baking sheet. Preheat the oven to 300 degrees Fahrenheit. Toast the bread for 20-30 minutes until it feels dry to the touch, any longer than that and you'll have croutons!