Begin by sautéing the sweet yellow onion and celery in a large skillet with 1 tablespoon olive oil and 1 tablespoon butter over medium heat until translucent and tender. Remove from heat and let cool slightly.
Spread the slivered almonds on a baking sheet and toast in the oven at 350°F (175°C) for 5-7 minutes, watching closely to avoid burning.
In a mixing bowl, combine diced cooked chicken, sautéed onion and celery, toasted almonds, lemon juice, mayonnaise, sour cream, cream of chicken soup, water chestnuts, herbs, black pepper, and smoked paprika. Mix well. Reserve 1/2 cup shredded cheese for topping.
Place the unbaked pie crust into the baking dish. Pour the chicken salad mixture into the crust and spread evenly. Sprinkle the reserved shredded cheese on top.
Preheat oven to 375°F (190°C). Bake the pie for 30-35 minutes until crust is golden and cheese melted and bubbly.
Remove the pie from oven and let cool for 10-15 minutes before slicing and serving.