Simpler Shrimp Bisque

I've never met a bisque I didn't like.

"To build a shrimp bisque with real shrimp flavor, we didn’t toss out the shrimp shells. Instead we sautéed them until bright pink, added mirepoix, and made a quick shrimp stock. This shrimp stock formed the base of our bisque. Heavy cream added richness, and a little sherry rounded out the flavor. Finally, to keep the shrimp from overcooking and becoming rubbery, we added them off the heat and let the residual heat of the bisque gently cook them though. Serves 6 to 8."

4 tablespoons unsalted butter
2 pounds medium-large (31-40) shrimp, peeled and shells reserved, shrimp deveined and chopped
2 onions, chopped
2 carrots, peeled and chopped
2 celery ribs, chopped
1/2 cup all-purpose flour
6 tablespoons tomato paste
2 garlic cloves, minced
2 cups dry white wine
6 cups water
2 sprigs fresh thyme
2 cups heavy cream
1 tablespoon dry sherry
Salt and pepper

1. Melt butter in Dutch oven over medium heat. Cook shrimp shells until spotty brown, about 5 minutes. Add onions, carrots, and celery and cook until browned, 6 to 8 minutes. Stir in flour and cook, stirring constantly, until golden, about 2 minutes. Add tomato paste and garlic and cook until fragrant and paste begins to darken, about 2 minutes. Stir in wine and simmer, scraping up any browned bits, until thickened, 2 to 3 minutes. Add water and thyme and bring to boil. Reduce heat to medium-low and simmer until slightly thickened, about 30 minutes.

2. Strain contents of pot through fine-mesh strainer into large saucepan, pressing on solids to extract as much liquid as possible; discard solids. Stir in cream and sherry and bring to simmer. Off heat, add chopped shrimp, cover pot, and let sit until shrimp are cooked through, about 5 minutes. Season with salt and pepper to taste, and serve.