Preheat the oven to 350°F.
Put the bread into a large mixing bowl and add the milk. Press the bread into the milk and let sit until the milk is absorbed and the bread is soft, about 15 minutes.
Heat 3 tablespoons of the olive oil in a large (12-inch) skillet over medium-high. Add the ground beef, and cook, stirring, until lightly browned, about 1 minute. Add the sausage and cook, stirring, until browned, about 3 minutes. Add the onions, bell peppers, celery, and bay leaf. Season with the salt, crushed red pepper and black pepper. Cook, stirring occasionally, until the vegetables are slightly softened, about 4 minutes. Add the garlic and cook, stirring, until fragrant, about 30 seconds.