Bring a large pot of salted water to a boil. Add the 12 oz of cheese tortellini and cook according to package instructions until al dente, usually about 3-5 minutes. Drain well and set aside.
In a large mixing bowl, combine the softened cream cheese, sour cream, minced garlic, onion powder, salt, and pepper. Mix until smooth and creamy. Fold in the chopped fresh spinach and drained, chopped artichoke hearts, stirring gently to combine.
Add the cooked tortellini to the bowl with the creamy spinach-artichoke mixture. Toss carefully to coat all the pasta pieces evenly.
Transfer half of the tortellini mixture to the baking dish. Sprinkle half of the shredded mozzarella and grated Parmesan over the top. Add the remaining tortellini mixture and finish with the remaining mozzarella and Parmesan cheese.
Preheat your oven to 375°F (190°C). Bake the tortellini casserole for 20-25 minutes, until the cheese is melted, bubbly, and slightly golden on top.
Remove from the oven and let it cool for a few minutes. Sprinkle the chopped green onions over the top as a fresh garnish. Serve warm and enjoy!
