Heat the olive oil and 1 Tablespoon of butter in a pot over high heat. Add the onions, celery, and bell peppers. Cook, stirring occasionally, until the onions begin to brown.
Reduce heat to low. Add the garlic, salt, sweet basil, thyme, cayenne, and black pepper. Cook, stirring occasionally, for 1-2 minutes.
Add the green onions and crawfish tails. Cook, stirring occasionally, for 2-3 minutes.
Add the Blue Runner® Creole Etouffée Base. Turn heat to high and bring the mixture to a boil. Reduce heat to low and simmer for 2-3 minutes. Add the 2 Tablespoons of butter and cook just until the butter melts into the sauce. Serve with cooked Chef Frank's Perfect Rice.