Preheat oven to 375 degrees.
Combine 1/4 cup yogurt,1/4 cup of cilantro, half of the lime juice, cayenne pepper and garlic. Coat chicken breast with this mixture, marinate for at least 1 hour.
While chicken marinates, purée remaining yogurt, 2/3 of cubed mango, 1/2 teaspoon lime juice and 1 cup cilantro in blender.
Bake chicken in a glass baking dish for 25-30 minutes.
Place chicken on serving plates, pour on sauce and sprinkle with mango and extra sauce on side.
Add a sprig of fresh cilantro for garnish.