HEAT oven to 350°F. Spray 13x9-inch baking pan with no-stick cooking spray. Melt butter in large saucepan over medium-high heat and add oil. Add onion and saute until soft, about 5 minutes. Add garlic and continue cooking 1 minute.
STIR in flour with a whisk, then gradually add half-and-half. When the sauce thickens, add Romano cheese and capers and stir until cheese is melted. Season with salt and pepper. Add scallops and shrimp and cook 3 to 4 minutes. Turn off heat.
SPOON about 2 to 3 tablespoons sauce into prepared pan. Cover bottom of pan with 4 noodles, placing them side by side. Spoon one third of sauce mixture over noodles. Layer 4 more noodles and 1/3 sauce mixture. Cover with remaining noodles and sauce. Sprinkle with Parmesan cheese.
BAKE 20 minutes, uncovered, until bubbly. Allow to rest 15 minutes before slicing.