To prepare seafood stuffing, heat margarine in a frying pan and sauté onion and garlic in it for just 2-3 min.
Add Pollock fillets and cook for 10 min on medium heat.
Now add shrimps and celery and cook for 2 min on high heat so that all water would have been absorbed.
Remove the pan from heat and then add rest of the ingredients including shrimp base, peppers, crab meat, croutons and bread crumbs and mix them well.
Take a greased baking tray and place the mushroom caps in such a way that their stem side up, one by one stuff the mushroom caps with prepared seafood stuffing, pour 1 tbsp of Alfredo sauce on each topping, sprinkle some Parmesan cheese and then place in oven to broil for 10 min until become light brown from top.
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