Preheat the oven to 400~. Line a baking sheet with foil and spray with cooking spray. Bake the cod fillets, uncovered, for 5 to 6 minutes, only until the cod flakes easily. Remove from the oven immediately to prevent overcooking. Whel cooled, break the fillets in half, lengthwise, then break each half into approximately 1" pieces and set aside. SAUCE-In a heavy non-aluminum 3-qt pot, melt the butter, add the flour and cook on moderate heat for 3 minutes, stirring constantly with a wire whisk. Do not allow the flour to brown. Add the milk and salt and bring to just below the boiling point, whisking constantly. Remove from the heat and keep warm (180~). Heat the olive oil in a saute pan over medium heat until fragrant, then saute the garlic only until white throughout. Add the sauteed garlic to the warm bechamel sauce. Add the sherry to the pan in which the garlic was sauteed, simmer strongly for 1 minute, then add it to the warmed sauce. Add the cooked pasta to the sauce. Place the bechamel/garlic/pasta/sherry mix back onto low heat for a few minutes, then add the cooked cod, clams, langostinos or shrimp, crabmeat and chopped parsley to the warm bechamel sauce and blend all ingredients thoroughly. Serve immediately.