Peel and devein shrimp, reserving shells. Coarsely chop shrimp, cover, and refrigerate.
In a medium stockpot, heat olive oil and butter over medium-high heat. Add onion, carrot, celery, and reserved shrimp shells. Reduce heat to medium-low. Cook, stirring occasionally, until vegetables are tender, approximately 10 minutes.
Add tomato paste and then flour. Cook on low for 5 minutes, stirring occasionally. Add seafood stock, thyme, bay leaf, orange peel, and cream. Bring to a boil, stirring occasionally, and reduce heat to a simmer. Cook for 45 minutes.
Strain stock through a fine-mesh sieve, discarding solids, and return to pot. Add salt, pepper, and chopped shrimp. Bring to a simmer, and cook just until shrimp turn opaque and pink, 2 to 3 minutes. Add sherry, stirring well.
Garnish individual servings with fresh thyme, if desired.
Notes
Make-Ahead Tip: Shrimp bisque can be made a day in advance, covered, and refrigerated. Before serving, reheat gently just until hot.
Recipe by TeaTime Magazine at https://teatimemagazine.com/shrimp-bisque-recipe/