In a medium saucepan, melt 3 tablespoons butter over medium heat. Whisk in the flour and cook for 1 minute, then whisk in the milk and cream and heat through, about 10 minutes. Lower the heat and stir in the sherry, paprika and nutmeg; season with salt and pepper. Cook, stirring, until thick enough to coat the back of a spoon, about 15 minutes.
Preheat the broiler. Season the scallops, shrimp and crab with salt and pepper. Season the crab with the Old Bay. In a large nonstick skillet, heat the EVOO, 1 turn of the pan, over high heat. Add the scallops and cook, turning once, until browned on each side, 4 to 6 minutes; transfer to a plate. Add the shrimp to the skillet and cook for 3 minutes on each side. Add the crab for the last 3 minutes of cooking and heat through. Return the scallops to the pan, pour the sauce evenly over the seafood and remove from the heat.
Arrange the bread on a baking sheet and toast in the broiler on each side, then spread with the remaining 2 tablespoons butter. Halve each piece of toast to make triangles. Place 4 toast triangles on each of 4 dinner plates, spoon the seafood Newburg on top and sprinkle with the chives and almonds.