Preheat oven to 350 degrees F and grease an 11 x 7-inch baking pan.

In a pot of boiling water, cook tortellini for 3 minutes.  You don't want it fully cooked because it will cook more in the oven. Drain and place in a bowl. Toss with 1 tablespoons of butter to prevent sticking.

Combine the the marinara, cream, and 1/2 cup Parmesan cheese.  Then add to the pasta and gently toss until coated. Season with salt and pepper if desired.

Place the tortellini into the greased baking dish. Sprinkle with remaining 1/2 cup Parmesan cheese and mozzarella.  Then bake uncovered for 25 minutes at 350 degrees or until lightly browned.