Preheat the oven to 350°F.
Prepare a 9x13-inch baking dish by spraying it with cooking spray. Place the torn pieces of bread evenly in the dish.
In a large mixing bowl, whisk together the heavy cream, half and half, pumpkin puree, granulated sugar, melted butter, eggs, vanilla extract, and pumpkin pie spice until smooth and well combined.
Slowly pour the custard mixture over the bread pieces in the baking dish, ensuring all the bread is evenly coated.
Bake in the preheated oven for approximately 1 hour, or until the bread pudding is set and the top is golden.
While the bread pudding is baking, prepare the praline sauce. In a heavy saucepan over medium-low heat, combine the butter, heavy cream, and brown sugar. Stir the mixture and bring it to a gentle boil.
Reduce the heat to low, add the chopped pecans, and stir. Allow the sauce to simmer for about 5 minutes, or until it thickens slightly.
Once the bread pudding is done, remove it from the oven and let it cool slightly. Pour the warm praline sauce over the bread pudding before serving.