To prepare the mango-lime butter, in a small saucepan, combine the chopped mango, wine, sugar, ginger and lime juice. Simmer over medium heat for about 8 minutes, or until it becomes syrupy.
Add the cream and mix well. Remove from the heat and pour into a blender. Blend until smooth. Return to the saucepan and simmer over low heat for about 10 minutes. You want the sauce to thicken a little.
Add the butter, one piece at a time stirring after each addition until well incorporated. Do NOT boil the sauce or it will separate.
Preheat a grill or grill pan to medium high heat (450 degrees F).
Pat dry the fish and brush with olive oil on both sides. Season with salt, ground black pepper and Italian seasoning.
Place the fish on the hot grill and cook for about 4-5 minutes on the first side then, flip it and cook for 3-4 minutes or until opaque. Remove from the grill.
Serve the fish with the mango butter-wine sauce.