If not using pre-cooked chicken, poach 1 lb boneless skinless chicken breasts in simmering water or broth for 12–15 minutes until cooked through. Let rest 5 minutes, then shred with two forks. Measure 3 cups shredded chicken and transfer to a large mixing bowl.

Make the dressing

In a medium bowl whisk together 1 cup mayonnaise, 1/4 cup Greek yogurt, 2 tablespoons minced Calabrian chiles (include some oil for flavor), 2 tablespoons lemon juice, 1 teaspoon lemon zest, 1 teaspoon Dijon mustard, and 1 tablespoon extra-virgin olive oil until smooth.

Build the salad

To the bowl with shredded chicken add the dressing and stir to coat evenly. Fold in 1/4 cup finely diced red onion, 1/2 cup diced celery, 1 cup seeded and diced plum tomatoes, 1 teaspoon chopped capers, 2 tablespoons chopped flat-leaf parsley and 1 tablespoon sliced basil if using. Add 1 clove minced garlic, 3/4 teaspoon salt, 1/2 teaspoon freshly ground black pepper, and 1/4 teaspoon crushed red pepper flakes if you want extra heat. Taste and adjust salt, pepper, or Calabrian chiles to your preference. If mixture seems dry, add up to 1–2 tablespoons extra olive oil or a little more yogurt.

Chill briefly

Cover the bowl and refrigerate the chicken salad for at least 20 minutes to let flavors meld. You can make it up to 24 hours ahead; hold lettuce separately.

Assemble Lettuce Cups & Serve

Prepare lettuce: separate 12 butter lettuce leaves, rinse and spin or pat dry. Arrange leaves on a serving platter with the cup side up.

Portion salad: Spoon about 2–3 tablespoons of the chilled Calabrian chicken salad into each lettuce leaf (approximately yields 12 cups). Slightly mound the mixture in the center of each leaf so it holds.

Garnish: Top each cup with a few microgreens or a little baby arugula if using. Drizzle a scant 1 teaspoon extra Calabrian chile oil over some cups for extra heat and flavor. Add a small lemon wedge to the platter for squeezing.

Serve: Transfer to plates and serve immediately so lettuce remains crisp. Leftover chicken salad will keep refrigerated in an airtight container for 3 days.