In large pot of boiling water, cook pasta shells according to package directions; drain. Preheat oven to 375°F. Grease 13- x 9-inch baking dish; pour in half of the pizza sauce.
Meanwhile, stir together ricotta, egg, garlic and oregano. Stir in half each of the mozzarella and Parmesan cheese.
Spoon filling evenly into cooked pasta shells; arrange in prepared baking dish. Spoon remaining pizza sauce over top. Sprinkle with pepperoni, and remaining mozzarella and Parmesan.
Cover with foil; bake for 30 minutes. Uncover and bake for about 10 minutes or until top is golden brown, and filling is bubbling and heated through. Sprinkle with parsley.
Tip: For easy entertaining, the pasta bake can be assembled in the baking dish, covered and refrigerated for up to 24 hours before baking.
A Pasta Fits original recipe.
National Pasta Association Recipe