In a small skillet, melt 1 stick of butter and add cubed cream cheese.Stir over low heat until cheese is melted. Set aside.
In dutch oven,melt 2 tablespoons butter and saute onions, bell pepper and mushrooms until vegetables are tender. Add shrimp just until heated.
Add the mushroom soup and 2 cups of rice. If too soupy more rice can be added later. Add cream cheese mixture to seafood mixture. Stir and season to taste with garlic powder and pepper. Add more cooked rice if needed.
Place mixture in greased (4-quart) casserole. Top with Velveeta cheese and fried onion rings.
Bake at 350 degrees for about 30 minutes or until bubbly.