Preheat oven to 375°F (190°C).

Cook manicotti shells according to package directions.

Rinse cooked shells with cold water to stop cooking.

Drain cooked manicotti shells and set aside.

In a mixing bowl, combine cottage cheese, herb-seasoned stuffing mix, and beaten egg.

Add drained mushrooms, chopped green pepper, grated Parmesan cheese, snipped parsley, and 1 1/2 tsp snipped chives to the cheese mixture.

Mix all ingredients thoroughly to combine.

Stuff each cooked manicotti shell with the cheese mixture.

Pour tomato sauce into the bottom of a baking dish.

Arrange the stuffed manicotti shells in the baking dish over the tomato sauce.

Sprinkle with garlic powder, Italian seasoning, and 2 tsp snipped chives.

Bake in the preheated oven for 30-40 minutes, or until golden brown and heated through.