In a large saucepan, melt the butter over medium heat. Add the onions, bell peppers, and celery and season with 1 teaspoon of the salt and 1/2 teaspoon of the cayenne. Cook, stirring, until the vegetables are wilted, about 10 minutes. Stir in the bay leaves, tomatoes, garlic, and 1/2 teaspoon of the salt. Increase the heat to medium-high and bring to a boil, then reduce the heat to medium-low. Simmer, uncovered, for about 35 minutes, stirring occasionally.

Combine the flour and water in a small bowl and whisk to blend. Add a small amount of the hot tomato sauce to the flour mixture and stir to blend, then whisk the mixture into the hot tomato mixture in the pan and continue to cook for 4 to 6 minutes, until thickened slightly, stirring occasionally.

Season the shrimp with the remaining 1 teaspoon salt and 1/4 teaspoon cayenne. Add to the pan along with the Worcestershire and hot sauce and cook over medium heat until the shrimp turn pink and curl slightly, 4 to 6 minutes. Stir in the green onions and parsley. Keep warm over very low heat.

To poach the eggs, pour cold water into a 10-inch sauté pan to a depth of about 2 inches. Bring to a simmer, then reduce the heat so that the surface of the water barely shimmers. Add the vinegar. Break 4 of the eggs into individual saucers, then gently slide them one at a time into the water and, with a large spoon, lift the white over the yolk. Repeat the lifting once or twice to enclose each yolk completely in the white. Poach until the whites are set and the yolks feel soft when touched gently, 3 to 4 minutes. Repeat the process until all of the eggs are used. You may have to add more water to keep the depth at 2 inches, but remember, the water must be simmering before adding the eggs. The eggs can be poached ahead of time and kept in a shallow pan of cool water. Reheat the eggs by slipping them into boiling water for about a minute.

To serve, arrange 2 slices of the toasted bread in the center of each serving plate. Remove the bay leaves from the sauce, and then spoon equal amounts of the shrimp Creole over the bread. With a slotted spatula, gently lift the eggs out of the water, let them drain for a few seconds, and transfer 2 eggs to top each shrimp Creole serving. Drizzle with the hollandaise sauce and serve immediately.