01 - Preheat the oven to 375°F. Lightly grease a 9x13-inch baking dish.
02 - Cook the jumbo pasta shells in salted boiling water according to package directions until al dente. Drain and set aside.
03 - In a large skillet over medium heat, cook ground beef until browned. Add onion and garlic; sauté until softened, about 2-3 minutes. Season with Italian herbs, salt, and pepper. Remove from heat, let cool slightly.
04 - In a large bowl, combine ricotta cheese, egg, Parmesan, 1 cup mozzarella, and parsley. Fold in the cooled beef mixture until well blended.
05 - In a separate bowl, mix marinara sauce and heavy cream. Spoon half the sauce mixture into the bottom of the prepared baking dish.
06 - Fill each pasta shell with about 2 tablespoons of the beef-ricotta mixture and arrange them in the baking dish.
07 - Pour the remaining sauce evenly over the stuffed shells. Sprinkle with 1/2 cup mozzarella and 2 tbsp Parmesan.
08 - Cover with foil and bake for 25 minutes. Remove foil and bake uncovered for 10 minutes, or until the cheese is bubbly and golden.
09 - Let rest for 5 minutes before serving. Garnish with extra parsley if desired.