Pressure cooking ups the creamy, custardy nature of this classic brunch staple. If you prefer a crispy crust for contrast, just pop the baking dish under the broiler with some sugar on top.
Special equipment: a 6- or 8-quart Instant Pot® multi-cooker. Cook’s Note: Settings may vary on your Instant Pot® depending on the model.
Preheat the oven to 300ºF. Grease an 8-inch round baking dish (3-quart) with the butter. Set aside.
Add the bread cubes to a baking sheet and bake until beginning to dry and harden, about 20 minutes.
Whisk together the cream, milk, sugar, vanilla, salt, cinnamon, whole eggs and yolks in a large bowl. Add the bread and raisins, if using, and stir until completely coated.
Pour the bread mixture into the prepared baking dish. Tear off a large piece of aluminum foil, about 1 1/2 feet long, and put the baking dish in the center. Wrap the foil around the dish, folding down the sides as needed so the top of the dish isn’t covered. Tear off a second piece of aluminum foil, about 2 feet long, and lay the foil in front of you with one of the longer sides closest to you. Fold the foil in half toward you the long way, then in half once again, to create a foil sling for the baking dish.
Add 2 cups water to a 6-quart Instant Pot® and set the rack in the bottom. Put the baking dish in the center of the foil sling, then pick up both sides of the sling and bring them up the sides of the baking dish. Carefully lower the dish onto the rack. Fold down the foil sling as needed so it fits in the pot but does not touch the pudding.
Follow the manufacturer’s guide for locking the lid and preparing to cook. Set to pressure cook on high for 45 minutes (see Cook’s Note).
After the pressure-cook cycle is complete, follow the manufacturer’s guide for quick release and wait until the quick-release cycle is complete. Being careful of any remaining steam, unlock and remove the lid.
If preferred, for an extra-crispy crust on top, sprinkle 1/4 cup granulated sugar on top of the dish. Place under the broiler for 5 minutes, or until the sugar caramelizes.
Let cool slightly before serving. Serve warm, at room temperature or cold.