Preheat oven to 350°F (180°C).

In a large skillet, sauté the onions in 1 Tbsp butter until just golden. Add spinach, salt, and garlic powder. Stir for 1 minute. Remove from flame and add cottage cheese and egg and mix well. Gently add the Parmesan cheese.

Stuff the raw cannelloni with the spinach-cheese mixture and place in a 9×13-inch pan. Pour the cream on top and sprinkle shredded cheese over everything.

Bake covered for 40 minutes. Uncover and continue baking until the cheese becomes golden, about 10–15 minutes.