Combine potatoes, corn, onion, garlic, oil and salt and pepper in a large bowl. Spread mixture evenly on a large cookie sheet.
Roast for approximately 30 minutes, until potatoes are cooked and slightly crispy. Transfer to a large bowl and add chicken, toss lightly to combine. Set aside.
In a small bowl, combine mayonnaise, sour cream, parmesan cheese, horseradish, lemon juice and dill. Toss potato and chicken mixture with the dressing and the bacon.