Peel shrimp, devein, leaving tails on and reserve the heads and shells.
Refrigerate the shrimp.
In Dutch oven, add shrimp heads and shells with the 7 c. of water. Bring to boil, then reduce heat to medium. Stirring occasionally for 15 minutes. Skim any froth as it rises to surface.
Strain through a fine mesh sieve into a bowl and set aside.
Reserve 1 c. of the stock. Remaining stock can be refrigerated for 1 week or frozen up to 3 months.
In large skillet, melt 5 T. of butter over high heat.
Add rosemary, pepper, Cajun seasoning, shallot and garlic. Cook, stirring constantly, until fragrant, about 1 minute.
Add stock, Worcestershire, Tabasco, and lemon juice.
Add shrimp and cook just until pink and firm.
Add beer and cook 2-3 minutes more.
Decrease heat to low, add remaining butter. Gently stir until butter melts into the sauce.
Serve immediately with bread.
Recipe by Geaux Ask Alice! at https://geauxaskalice.com/famous-new-orleans-bbq-shrimp/