Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the sweet corn, mayonnaise, sour cream, lime juice, and chili powder until well blended.
Arrange the chicken breasts in a lightly greased casserole dish in a single layer.
Season the chicken with salt, garlic powder, and cayenne pepper if using.
Spread the prepared corn mixture evenly over each chicken breast.
Bake the Mexican Street Corn Chicken uncovered for 30–40 minutes, or until the chicken reaches an internal temperature of 165°F (74°C).
Remove from the oven and immediately sprinkle with crumbled queso fresco and chopped cilantro.
Serve hot with rice, roasted vegetables, or a fresh salad.