Cut the bread into 1-inch cubes and place them in a very large mixing bowl.
In another large bowl, add the milk and whisk in the espresso powder. Let it sit for a few minutes to dissolve, then whisk a second time. Next, add the eggs, sugar, and salt, and whisk until they are fully combined. Pour the mixture into the bowl with the bread cubes and make sure the cubes are mostly submerged. Place the bowl in the refrigerator to soak for at least 2 hours.
Preheat the oven to 350° F (180° C.) Spray a 2-qt baking dish, 8X8-inch, or 9X9-inch pan with baking spray, or line with parchment.
Add the white chocolate to the bowl of bread cubes and stir until it is evenly distributed. Pour the contents of the bowl into the baking dish and bake at 350° F (180° C) for about 35-40 minutes, or until the top of the pudding is lightly browned, and the center no longer jiggles.
The bread pudding should be stored in the refrigerator for no more than 4 days. If not serving immediately, you can reheat just before serving, or heat individual servings in the microwave.
