Place the chicken breasts in a saucepan and cover them with lightly salted water or chicken broth. Bring the liquid just to a gentle simmer, cover the pan, and cook for 12-18 minutes, depending on thickness, until the thickest part reaches 165°F (74°C).

Remove the chicken from the liquid and let it cool completely. Shred it or cut it into approximately 1/2-inch pieces once cool.

Toast the pecans or almonds in a dry skillet over medium heat for 3-5 minutes, stirring frequently. Transfer them to a plate so they cool and remain crisp.

Whisk the mayonnaise, Greek yogurt or sour cream, lemon juice, Dijon mustard, kosher salt, and black pepper in a small bowl. Add honey if you prefer a slightly sweeter dressing.

Combine the cooled chicken, grapes, celery, toasted nuts, onion, and herbs in a large bowl. Fold in the dressing gently until each ingredient is evenly coated without crushing the grapes.

Taste and adjust the seasoning with more salt, pepper, lemon juice, or honey as needed. Cover and refrigerate for at least 30 minutes; chilling for 1-2 hours gives the flavors more time to blend.

Serve the chicken salad in croissants, lettuce leaves, on toast, in avocado halves, or with crackers and Belgian endive. Garnish with extra herbs and a few chopped nuts just before serving.