Preheat oven to 350F, and spray a 9x13 pan with nonstick spray.
In a large bowl, whisk together the pumpkin puree, milk, cream, brown sugar, eggs, pumpkin spice, and salt.
Place about half of the bread in the dish, and pour half of the egg mixture on top, mixing lightly.
Top with the rest of the bread, and the rest of the liquid and mix until everything is evenly soaked.
If you have the time, allow the bread pudding to sit for at least 30 minutes before baking.
When ready, sprinkle the raw sugar on top, and bake for 40-50 minutes, until the middle is no longer jiggly and the top is golden brown.
Serve warm with whipped cream.