Preheat oven to 400 degrees.
Cook macaroni to al dente stage according to package instructions. Drain and rinse to stop the cooking. Set aside.
Shred Gruyere in food processor and set aside.
Heat butter in a large skillet. Cook onion about 7 minutes until translucent. Sprinkle the flour over the onions and stir until flour is evenly absorbed.
Add the wine and let it simmer a few minutes. Add the cream and stir to mix the onions throughout. Add the cheese and stir constantly until sauce thickens, cheese is melted and bubbling. Add the fresh lemon juice and stir.
Mix the macaroni, cheese sauce, scallops and shrimp together in a large bowl.
Spray a 10" X 3" casserole dish with cooking spray. Transfer the macaroni mixture to the casserole. Sprinkle evenly with paprika and then spread panko evenly over the top.
Bake at 400 degrees for 40 minutes.