Preheat oven to 325 degrees F (165 degrees C).

Cook manicotti shells according to package directions; rinse and drain well.

Coarsely shred zucchini.

Melt butter in a skillet over medium heat.

Add shredded zucchini to the skillet and cook for 7-9 minutes, or until softened.

In a large bowl, combine the cooked zucchini, cottage cheese, and 1 cup of shredded Cheddar or Mozzarella cheese.

Mix well to combine all ingredients.

Stuff each cooked manicotti shell with the cheese and zucchini mixture.

Arrange the stuffed manicotti shells in a shallow 2-quart baking dish.

In a separate bowl, mix together the spaghetti seasoning mix, tomato paste, and boiling water until well combined.

Spoon the tomato sauce mixture evenly over the stuffed manicotti shells in the baking dish.

Cover the baking dish tightly with aluminum foil.

Bake in the preheated oven for 30-40 minutes.

Remove the foil from the baking dish.

Sprinkle the remaining shredded cheese (1 cup) evenly over the manicotti.

Bake uncovered for an additional 10 minutes, or until the cheese is melted and bubbly.

Just before serving, sprinkle with Parmesan cheese.