Remove any bones or skin from the chicken breasts. Cut into 1 inch cubes. There should be about 3 cups chicken and 2 cups shrimp all together. Set aside.
Heat half the butter in a Dutch oven over medium heat and add onion and garlic. Cook about 1 or 2 minutes, then add celery. Cook another minute then season with curry powder and stir. Add the tomato paste; stir. Add banana and apple; stir. Add the broth and stir until liquid is well blended. Salt to taste and simmer 10 minutes.
Heat the remaining butter in a saucepan. Add the chicken. Season with salt and pepper. Cook about 2 to 3 minutes. Add shrimp and cook an additional 2 minutes, stirring.
Meanwhile, pour the curry mixture into the bowl of a food processor or blender and process until smooth. Can also be done with an immersion blender.
Pour the sauce over the chicken and shrimp, heat 2 minutes and serve.