Preheat the oven to 375°F (190°C).
Bring a large pot of salted water to a boil.
Cook jumbo shells until just slightly under al dente.
Drain and rinse the shells with cool water.
Set the pasta aside to cool slightly.
Heat olive oil in a skillet over medium heat.
Add minced garlic and cook for about 1 minute.
Add spinach and cook until wilted.
Remove from heat and allow the mixture to cool.
In a mixing bowl combine ricotta cheese, Parmesan, half of the mozzarella, cream cheese, egg, salt, pepper, basil, parsley, and oregano.
Stir until the mixture is smooth.
Fold in the cooled spinach and garlic mixture.
Spread half of the marinara sauce on the bottom of the baking dish.
Fill each pasta shell with the ricotta mixture.
Arrange the stuffed shells in the baking dish.
Spoon remaining marinara sauce over the shells.
Sprinkle remaining mozzarella cheese over the top.
Cover and bake for 20 minutes.
Remove the cover and bake another 10 minutes until cheese is melted and golden.
Garnish with fresh parsley before serving.