Cut and place the bread cubes In a large bowl, set aside.
In a small saucepan, combine cream, sugar, and cinnamon over medium heat until steaming but not boiling. Remove from heat and add vanilla.
In a liquid measuring cup, whisk eggs. Slowly temper the egg mixture by adding ⅓ of the hot cream mixture and whisking continuously. Slowly add the egg mixture back to the rest of the heavy cream mixture and whisk to combine.
Pour the cream mixture through a strainer over the bread pieces to remove any lumps. Fold the hot cream into the bread and allow all the pieces to get coated. Be careful not to over mix and create a slimy mush. Soak for about 5 minutes.
Divide the bread mixture into 4-6 small ramekins, or 2, 6 inch cake pans. Cover each pan tightly with foil.
Place the trivet and 1 cup water in the Instant Pot, and stack the ramekins or baking pans evenly. If using the cake pans, use a trivet, two chopsticks, or a pressure cooking sling/silicone steamer to create a gap between the two cake pans. Do not stack the two cake pans directly on top of each other without something separating them.
Cook for 30-35 minutes on manual high pressure (30 min for ramekins, more time for larger cooking pans), and then allow a 5-10 minute natural pressure release. Then, release the rest of the pressure and carefully remove from the Instant Pot.
Enjoy with berries, whipped cream, and butter rum sauce.