Preheat your oven to 350 degreese F.
Prepare your 9x13 pan by spraying it with cooking spray. Spread almost 1/2 of the jar of marinara sauce on the bottom of the pan. Set the pan aside.
Fill a large pot with water. Add salt and bring the water to a boil. Add the jumbo pasta shells and cook until very al dente. I would say 3-5 minutes under what the box says to cook them. The noodles will continue cooking in the oven, so trust me you don't want to over cook them.
Drain your pasta shells in a colander. Allow them to set for at least 5 minutes before starting to stuff them.
In a large bowl mix together the cottage cheese, Parmesan cheese, mozzarella cheese, egg, basil leaves, salt, pepper, red pepper flakes, and garlic powder.
Use a spoon to stuff the filling in the shells. Place the shells in the pan with the marinara sauce on the bottom.
Once your shells are stuffed, top them with the rest of the marinara sauce. Sprinkle mozzarella cheese on top.
Bake for 30 minutes or until the shells are bubbly and cheese has melted. Serve immediately.