Sauté shrimp in butter. Season with salt and pepper. Repeat same process with scallops. Combine all seafood.
Strain the juices out, and combine with the velouté sauce. Simmer seafood in sauce for a while. Season to taste. Add the cooked potatoes, and carrots. Mix in the mayonnaise, sour cream, and Worcestershire. Spoon in casserole dish. Sprinkle breacrumbs over top. Drizzle with butter.
Bake at 350 F. for about 25 minutes or until bubbly.