While the shells cook, preheat the oven to 375° F. Line a large baking sheet with a piece of parchment paper.

Using a large bowl, mix the ricotta cheese, olive oil, garlic powder, oregano, basil, parsley, breadcrumbs, ½ cup Parmesan cheese, 1 teaspoon Kosher salt, and ½ teaspoon of black pepper together until well-combined. Stir in the chicken. Season with salt and pepper to taste.

Pour the marinara sauce, water (see Note), and heavy cream into the bowl of a food processor fitted with the blade. Process for about 10 seconds, until smooth. Transfer all of the sauce to the bottom of an oval baking/casserole dish.

When the shells are finished cooking, drain them well. Dump the shells onto the parchment-lined baking sheet and gently separate those that have stuck or nestled together. Make sure they are not touching each other.

Using a soup spoon, scoop about 3 tablespoons of filling. Take a shell in one palm with the shell ends facing your pinky and thumb. Place the long side of the spoon inside the shell, along the long side of the shell. Slide the filling into the shell with your fingers. The shell should be filled to the top but not bursting out the sides. Place the shell back on the baking sheet. Repeat with the remaining shells and filling.

Arrange the filled shells in a circular pattern around the outer edge of the dish with an end facing the center of the dish, nestling them into the sauce as you go. Squeeze the last few shells into the center space of the dish - there should only be 3 or 4 left at this point. Don’t throw the parchment paper away - you’ll use it for baking. At this point, you can cover and refrigerate the shells to bake later or bake them off right away.

Cover the dish loosely with a piece of foil. Place the casserole dish on a parchment-lined baking sheet (it can be the same one you used for prepping the shells).

Bake for 45 minutes. Turn up the oven to 400° F. Remove the foil and sprinkle the mozzarella and remaining Parmesan cheese over the top of the shells. Continue baking for another 10 minutes. Turn the oven up to 425° F and bake for another 7 to 8 minutes, until the top of the cheese has just started to brown in places and the edges of the shells have just started to become crispy.

Remove the dish (still on the baking sheet) from the oven. Allow the shells to cool and set on the baking sheet for about 10 minutes before sprinkling with extra basil and parsley and serving.