In a large mixing bowl, whisk together all of th eingredients except for the bread and blueberries.
Grease a 1.5 quart Corningware casserole dish with butter or cooking spray and place the cubed bread inside of it. Pour the egg and cream mixture all over the bread, add in the bluberries, slightly pressing down on some as you toss them in. Use a spatula to mix this well so all of the bread is coated.
Wrap the casserole securely with aluminum foil. Place two cups of water in the Instant Pot and place the metal rack (that comes with the Instant Pot) inside. Place the casserole ontop of the rack. Close the lid on the Instant Pot, and high pressure cook for 30 minutes. Once the Instant Pot has finished pressure cooking, quick release after 15 minutes and open the lid carefully. Once it cools down slightly, use oven mits to remove the rack and casserole from the Instant Pot.
Open up the foil. Let it rest for about 5 minutes and then serve warm with some additional lemon zest on top and a sprinkle of confectioner's sugar and side of maple syrup! If you want a more golden crisp top, you can place the casserole under the broiler in the oven for 2-3 minute as well.