Cut bread into ¾ inch cubes. Place in a very large bowl.
In a separate bowl, whisk together the eggs, milk, 1 cup cream, sugar, vanilla, zest and salt until the sugar has dissolved. Pour the egg mixture over the bread; toss to coat. Cover with plastic and place a plate on top to submerge the bread in the egg mixture. Chill at least 4 hours or overnight.
When ready to bake, stir the bread mixture once again and then let it stand at room temperature for 30 minutes.
Preheat the oven to 375 degrees F. Spray a 13x9 inch dish with nonstick spray.
Transfer the bread mixture to the prepared dish (use an extra small baking dish too if there is too much to fit into the pan). Sprinkle lightly with cinnamon. Bake until puffed and golden and toothpick inserted into center comes out clean, about 40 minutes. Cool slightly.
Using an electric mixer, beat the remaining 1 cup of cream and the powdered sugar in a medium bowl until peaks form.
Cut the pudding into 16 slices. Serve puddings warm or at room temperature with whipped cream and warm caramel sauce.
Notes
Note: "Whipping Cream" is not the same thing as Cool Whip. Look for liquid cream in a carton near the milk products.
DO AHEAD: Let puddings stand at room temperature up to 2 hours until ready to serve. Leftovers heat up well too!