How to Make It
Preheat the oven to 400°. In a pie plate, toss the bread cubes with the olive oil and season with salt. Bake for 8 minutes, or until golden brown. Let cool completely. Transfer the bread cubes to a sturdy plastic bag and crush them with a rolling pin until coarse crumbs form. Reduce the oven temperature to 350°.
Meanwhile, bring a large, deep skillet of salted water to a boil. Add the asparagus and boil until just tender, about 5 minutes. Drain the asparagus. Transfer the asparagus to a large gratin dish.
Bring a medium saucepan of water to a boil. Add the eggs and boil over moderate heat for 5 minutes. Pour off the water and gently shake the saucepan to crack the egg shells. Fill the saucepan with ice water and let the eggs cool for 5 minutes, then drain. Carefully shell the eggs and transfer them to a plate.
In a small saucepan, cook the butter over moderate heat until it smells like roasted hazelnuts and the milk solids are lightly browned, about 7 minutes. Remove the pan from the heat and let the brown butter cool slightly.
Bring a medium saucepan of water to a simmer over moderate heat. In a blender, combine the egg yolks and the 1 1/2 tablespoons of hot water; blend for 2 seconds. With the blender on medium speed, gradually add the hot brown butter, a few drops at a time at first and then in a thin stream, until fully incorporated. Add any browned bits from the bottom of the pan, then add the lemon juice. Season the hollandaise with salt, pepper and a pinch of cayenne.
Reheat the asparagus in the oven. One by one, carefully lower the peeled whole eggs into the hot water in the medium saucepan and warm just until heated through, about 1 minute.
Meanwhile, arrange 4 of the asparagus spears on each of 4 plates. Pat the eggs dry and set one on top of each plate of asparagus. Spoon the hollandaise over the eggs and asparagus, sprinkle with the crushed croutons and serve right away.