To begin, preheat the oven to 400°F.
Cook the jumbo pasta shells halfway, according to the package directions. While the shells cook, in a large mixing bowl stir together ricotta cheese, drained spinach, chopped artichoke hearts, mozzarella cheese, parmesan cheese, egg, minced garlic, salt, pepper, and chili flakes. Set aside until shells are ready.
Once the pasta is halfway cooked, drain and toss with 1 Tbsp olive oil.
In a 9 x 13 inch baking dish pour about 2 ½ cups of marinara sauce in the base of the dish. Reserve the rest of the sauce for topping the shells.
Stuff each pasta shell with 1 regular sized tablespoon of stuffing and place them lined up in the baking dish.
When all shells are stuffed, top the shells with the remaining marinara sauce and them cover with mozzarella cheese. Bake for 20 minutes.
Remove from oven and cover. Allow the stuffed shells to cool a few minutes before serving. Garnish with fresh chopped basil.