Preheat the oven to 350°F (175°C) and spray a 9 x 13 baking dish with cooking spray.

Tear the day-old challah bread into small pieces and spread them across the bottom of the prepared baking dish.

In a large mixing bowl, combine the heavy cream, half and half, pumpkin puree, granulated sugar, melted butter, eggs, vanilla extract, and pumpkin pie spice. Whisk until smooth.

Pour the custard mixture over the torn bread, pressing down gently to ensure all pieces are soaked. Let sit for 10 minutes.

Bake for approximately 1 hour or until the top is golden brown and a knife inserted in the center comes out clean.

For the praline sauce, combine unsalted butter, heavy cream, and brown sugar in a saucepan. Bring to a boil, then reduce heat and stir in chopped pecans. Simmer for 5 minutes.

Serve warm or chilled, drizzled with warm praline sauce.