1 1/2 pounds shrimp; cleaned, deveined, and peel left on (if using frozen, thaw and drain)
4 cups chicken broth
7 Tablespoons (3 1/2-ounces) unsalted butter, divided
2 cups chopped leeks (white and light green parts), about 3 small-medium sized leeks
2 shallots, chopped
4 cloves garlic, peeled and chopped
1/4 cup Cognac or brandy
1/4 cup dry sherry
1/4 cup unbleached all-purpose flour
1 1/2 cups half-and-half
1/4 cup tomato paste
1 teaspoon kosher salt, plus more to taste
1/2 teaspoon freshly ground black pepper, plus more to taste
Cayenne pepper to taste

Garnish
A few reserved shrimp chopped into bite-size pieces
Chopped chives