Cook the chicken, if you're not using rotisserie. Season bone-in breasts and roast at 425 for 30 minutes. Let them cool before dicing.
Prep the cucumber. Shred half and squeeze it dry in a clean towel, then pat it down. Peel the other half, chop it, and drain it too.
Make the tzatziki. Stir together the labne, lemon juice, microplaned garlic and both the shredded and chopped cucumber. Season with the onion powder, salt and white pepper, and taste it now.
Fold everything in. Add the diced chicken and red onion, and fold gently.
Finish. Crumble the feta over the top with the parsley and dill, and fold once more.
Chill an hour if you have time. The garlic and dill need a little while in the labne.