Instructions

  1. Heat broiler, with rack set 4 inches from heat.
  2. Line a rimmed baking sheet with aluminum foil.
  3. In a medium bowl, combine buttermilk, lemon juice, garlic, and Parmesan.
  4. Season with salt and pepper.
  5. Place mixture in a resealable plastic bag; reserving 1/2 cup for salad, add the rest of the buttermilk mixture to bag.
  6. Refrigerate chicken at least 15 minutes and up to 1 day.
  7. Meanwhile, make croutons by placing bread on prepared baking sheet.
  8. Brush both sides with oil, and season with salt and pepper.
  9. Broil until toasted, 1 to 2 minutes per side; cut into 1 inch pieces (and reserve baking sheet).
  10. Transfer chicken to baking sheet; discard marinade.
  11. Broil until opaque throughout, 14 to 16 minutes.
  12. Let rest 5 minutes; thinly slice crosswise.
  13. In a large bowl, stir together mayonnaise and the reserved 1/2 cup of buttermilk mixture.
  14. Add romaine, radicchio, chicken, and croutons; toss to combine.
  15. Serve immediately.