Preheat oven to 375°F. Grease a 9x13 baking dish.
Brown ground beef in a skillet, drain excess fat, then cook onion 3 to 4 minutes. Add garlic, cook 1 minute. Stir in marinara, diced tomatoes, and spices. Simmer 8 to 10 minutes.
Cook tortellini in salted boiling water for 2 minutes less than package time. Drain.
Beat cream cheese with sour cream, parmesan, and garlic powder until smooth.
Layer half the meat sauce in the baking dish. Add tortellini, then dollop cream cheese mixture over the top and spread gently. Pour remaining meat sauce over everything. Top with mozzarella.
Cover with foil and bake 20 minutes. Remove foil and bake 10 to 15 more minutes until golden and bubbly. Rest 5 minutes before serving.