1. Preheat oven to 375°F (190°C). Carefully slice off the top 1 inch from each sourdough loaf to create a lid. Cut around the inside perimeter of each loaf, leaving a 1 inch border, then use your hands or a spoon to scoop out the soft interior bread, creating a hollow bowl. Tear the scooped out bread into bite sized pieces. Brush the inside and outside of each bread bowl, including the lids and the scooped out bread pieces, with olive oil. Place the hollowed bread bowls, their lids, and the bread pieces on a large baking sheet. Bake for 10-15 minutes, or until the bread bowls are lightly toasted and slightly firm. The bread pieces should be golden brown and crispy. Remove from oven and set aside.

2. Melt butter in a large pot or Dutch oven over medium heat. Add chopped onion and celery. Sauté for 5-7 minutes until they soften and become translucent. Stir in the minced garlic and cook for another minute until fragrant. Do not let the garlic burn.

3. Sprinkle all purpose flour over the sautéed vegetables. Stir constantly for 1-2 minutes to cook out the raw flour taste. This creates a roux, thickening the sauce. Gradually whisk in the whole milk, then the heavy cream, a little at a time, ensuring no lumps form. Continue whisking until the mixture becomes smooth and starts to thicken.

4. Reduce the heat to low. Add the softened cream cheese and whisk until it melts completely into the sauce, creating a rich, creamy base. Stir in the grated Parmesan cheese until it melts and incorporates smoothly. Season the sauce with Old Bay Seasoning, salt, and black pepper to taste. Adjust seasoning as needed.

5. Gently fold in the chopped cooked shrimp, lump crabmeat, and bay scallops (if using). Stir until the seafood is just combined. Avoid overmixing to keep the seafood intact. Stir in the fresh chopped parsley.

6. Carefully spoon the creamy seafood filling into each toasted sourdough bread bowl. Fill them generously. Sprinkle a little extra Parmesan cheese on top of the filling in each bread bowl. Place the filled bread bowls back on the baking sheet. Bake for 15-20 minutes, or until the filling is bubbly and heated through, and the tops are golden brown.

7. Carefully remove the seafood stuffed bread bowls from the oven. Garnish with additional fresh parsley, if desired. Serve immediately with the toasted bread lids and the reserved bread pieces for dipping.