Coarsely chop 6 shrimp. Place into a medium bowl.

Peel all remaining shrimp. Add removed shells to a bowl with chopped shrimp. Set bowl aside. Reserve peeled shrimp for another use. Store in a tightly sealed container, in the refrigerator, until ready to serve.

Place a large pot or Dutch oven over medium heat.

Add margarine and butter and cook until melted and hot but not burning.

Add onion, celery, garlic, chopped shrimp and shells. Cook, stirring, until shells begin to brown, about 10 to 15 minutes.

Stir in flour until well mixed.

Gradually whisk in water. Cook, whisking occasionally, about 7 minutes.

Pour mixture into a colander or sieve over a bowl to catch the liquid. Discard solids.

Pour strained liquid back into pot.

Place pot over medium heat. Cook and stir until the sauce thickens, about 10 minutes.

Add paprika, ground red pepper, 1/4 teaspoon black pepper and 1/4 teaspoon salt, or to taste. Cook about 10 minutes.

Taste. Adjust seasonings, to taste.

Add the bell peppers. Simmer 5 minutes.

Add cream and sherry. Whisk until combined.

Add crawfish meat. Cook until just heated through, about 1 minute.

Serve immediately, hot.