Add stock ingredients to water and bring to a boil; boil 20 to 30 minutes; remove from heat and strain. Discard solids reserving stock.
In a large skillet melt butter; add onions, celery and garlic. Sauté until vegetable are tender about 5 minutes.
Remove from heat; add tomato paste and flour. Stir gently to coat vegetables. Add basil, Cajun seasoning, everglade seasoning, cayenne, and paprika. Add half and half & 2 cups of the stock; whisk until well combined.
Return to heat; add bay leaf and hot sauce. Bring to a boil; reduce heat and simmer for 10 minutes. Add shrimp in the last 2 minutes. Shrimp will be pink when done.
Remove from heat and add green onions. Taste test; add additional seasonings if desired. Serve with crusty bread or crackers.