Peel and devein shrimp; set aside.
Heat olive oil in a large nonstick skillet over medium-high heat until hot. Add celery, green pepper, green onions, and garlic; saute 3 minutes. Add mushrooms; saute 1 minute. Stir in shrimp and scallops; saute 3 minutes or until shrimp turns pink and scallops are opaque. Remove from heat; stir in crabmeat and next 3 ingredients.
Combine milk and next 5 ingredients in a large bowl; stir in seafood mixture, rices, and almonds. Spoon mixture evenly into 2 (7- x 5 1/4- x 1 1/2-inch) baking dishes coated with cooking spray; sprinkle evenly with breadcrumbs. Bake, uncovered, at 350° for 20 to 25 minutes or until hot and bubbly.
To Serve Two: Thaw 1 casserole in refrigerator or microwave oven. Bake, uncovered, at 350° for 20 to 25 minutes or until hot and bubbly.