Bring a large pot of salted water to a boil and cook the shells until just al dente. Don’t overcook, as they’ll bake later. Drain and spread them out on a tray to cool so they don’t stick together.
While the pasta cools, mix the shredded chicken, softened cream cheese, ranch seasoning, buffalo sauce, half the mozzarella, and black pepper in a large bowl. Stir until smooth and creamy with an even distribution of chicken.
Gently open each shell and spoon the filling inside. Place them seam-side up in a greased baking dish, arranging them close but not overlapping.
Sprinkle the remaining mozzarella and cheddar over the stuffed shells. Bake at 350°F for 15–20 minutes until bubbly and golden. The aroma will make it hard to wait!
Remove from the oven and drizzle ranch dressing and extra buffalo sauce on top. Garnish with parsley or chives for color and freshness before serving warm.