Bring a large pot of salted water to a boil. Cook jumbo shells for 8 minutes (al dente). Drain, submerge in cool water, and lay flat on paper towels.

Heat 1 tbsp extra virgin olive oil in a skillet over medium heat. Sauté 4 cloves minced garlic for 1 minute. Add chopped shrimp and whole reserved shrimp, lemon zest, salt, and pepper. Sauté 2-3 minutes until pink and opaque. Remove from heat and set reserved whole shrimp aside.

In a mixing bowl, combine ricotta, 1/2 cup Greek yogurt, egg, Italian seasoning, 1/2 cup Parmesan, 1/2 cup mozzarella, and 2 tbsp parsley. Fold in the cooled chopped shrimp.

In the same skillet, heat 1 tbsp olive oil and sauté 3 cloves minced garlic for 1 minute. Add seafood stock and bring to a simmer for 3 minutes. Reduce heat to low, whisk in 1/2 cup Parmesan, then stir in 1/2 cup plain Greek yogurt until smooth and velvety.

Preheat oven to 375°F (190°C). Pour half of the garlic cream sauce into a 9x13 inch baking dish. Pipe or spoon filling into each shell and arrange open-side up in the dish.

Pour remaining garlic sauce over shells. Place reserved whole shrimp on top and sprinkle remaining 1/2 cup mozzarella.

Cover loosely with foil and bake for 20 minutes. Remove foil and bake 5 minutes more until bubbling and lightly golden.

Let rest 5 minutes. Garnish with remaining chopped parsley and cracked black pepper before serving.