Prepare the lobsters: Bring a large pot of salted water to boil. Add lobsters and cook for 8 minutes. Remove and let cool, then remove meat from shells, reserving both meat and shells.

Make the stock base: In a large pot, heat olive oil over medium heat. Add lobster shells and sauté for 5 minutes until fragrant. Add onions, carrots, celery, and garlic, cooking until softened (about 5 minutes).

Deglaze and simmer: Add tomato paste and cook for 1 minute. Pour in sherry to deglaze, scraping up browned bits. Add seafood stock, bay leaf, and thyme. Simmer for 20 minutes.

Strain and thicken: Strain the stock through a fine mesh sieve, pressing on solids. Discard solids. In a clean pot, melt butter, whisk in flour to make a roux. Gradually whisk in strained stock.

Finish the bisque: Bring to a gentle simmer, stirring constantly until thickened (about 5 minutes). Reduce heat, stir in cream and lobster meat. Heat through but do not boil.

Season and serve: Season with salt and pepper to taste. Ladle into bowls and garnish with fresh parsley. Serve with crusty bread.