Prep the chicken: Use leftover roast chicken or a rotisserie chicken. Chop or shred into bite-size pieces. You want about 4 cups.
If cooking from scratch, season chicken breasts with salt and pepper and poach or roast until just cooked through, then cool completely before chopping.
Toast the almonds (optional but recommended): Add sliced almonds to a dry skillet over medium heat. Stir often for 3–4 minutes until fragrant and lightly golden. Remove to a plate to cool.
This step deepens flavor and keeps them crunchy.
Mix the dressing: In a large bowl, whisk mayonnaise, Dijon, lemon juice, olive oil (if using), garlic powder, a pinch of paprika, and a few grinds of black pepper. Taste and adjust. You want a bright, creamy balance with a gentle Dijon bite.
Add the crunchy elements: Stir in the celery, red onion, and parsley.
Mix to coat evenly in the dressing.
Fold in the chicken: Add the chicken and toss gently until everything is well coated. If it looks dry, add another spoonful of mayo or a splash of lemon juice.
Finish with almonds: Fold in most of the almonds, reserving a few for garnish. Taste again and season with salt and more pepper if needed.
Chill and serve: For best flavor, chill for at least 20–30 minutes.
Serve in lettuce cups, spooned over greens, tucked into low-carb wraps, or alongside sliced cucumber and avocado. Garnish with the remaining almonds.