Step 1: Cook the Pasta Shells
Preheat your oven to 350°F (175°C). Bring a large pot of generously salted water to a boil. Add the jumbo shells and cook for about 9-10 minutes, or until they are al dente—still firm to the bite. They will continue to cook in the oven, and overcooking now will make them mushy and difficult to stuff. Drain the shells and immediately rinse them with cold water to stop the cooking process. This also makes them easier to handle. Drizzle with a tiny bit of oil to prevent sticking.

Step 2: Create the Creamy Filling
In a large mixing bowl, combine the softened cream cheese and sour cream. Use a hand mixer or a sturdy spoon to beat until smooth. Add the dry ranch seasoning packet, minced garlic, and black pepper, and mix well. Fold in the shredded chicken, 1 cup of the mozzarella cheese, all of the cheddar cheese, the crumbled bacon (reserve 2 tbsp for garnish), sliced green onions, and fresh herbs. Mix until everything is evenly and thoroughly combined.

Step 3: Prepare the Creamy Parmesan Sauce
In a medium saucepan, melt the butter over medium heat. Whisk in the flour and cook for 1 minute to form a roux. Gradually whisk in the warm milk and chicken broth until smooth. Cook, stirring constantly, until the mixture thickens and begins to gently bubble, about 5-7 minutes. Reduce heat to low. Stir in the grated Parmesan cheese and garlic powder until the cheese is melted. Season with salt and pepper to taste. The sauce should coat the back of a spoon.

Step 4: Assemble the Bake
Spread about ¾ cup of the creamy Parmesan sauce evenly over the bottom of a 9×13 inch baking dish. Take one cooked shell in your hand. Using a small spoon (a teaspoon or a piping bag works great), carefully fill the shell with the chicken-bacon-ranch mixture. Don’t overstuff, but pack it in firmly. Place the stuffed shell seam-side up in the prepared baking dish. Repeat with the remaining shells, arranging them snugly in a single layer.

Step 5: Sauce and Top the Shells
Pour the remaining creamy sauce evenly over the top of the stuffed shells, aiming to get some into the nooks and crannies. Sprinkle the remaining ½ cup of mozzarella cheese and the reserved bacon crumbles over the top.

Step 6: Bake to Bubbly Perfection
Cover the baking dish tightly with aluminum foil. Bake for 20 minutes. Then, remove the foil and bake for an additional 10-15 minutes, or until the cheese on top is melted and bubbly, and the sauce is bubbling around the edges.

Step 7: Rest, Garnish, and Serve
Remove the bake from the oven and let it rest for 10 minutes. This allows the filling to set slightly, making them easier to serve. Garnish with additional sliced green onions and fresh parsley. Serve warm, spooning extra sauce from the dish over each portion.