Heat stock on low. Season shrimp with Cajun seasonings and set aside. While stock warms, heat oil and 2 tbs butter in saucepan over medium heat. Add onions and garlic, saute until softened, 8-10 minutes. Stir in rice, cook for three minutes stirring often. Add wine to pan and cook until absorbed. Add 1/2 cup, or use a 6 oz ladle, of broth to rice. Continue adding the stock a ladle at a time, waiting until the liquid is absorbed before adding more. Add shrimp to rice before last cup of broth. Cook until the rice is tender and creamy and shrimp is cooked. Remove from heat, stir in Parmesan. Salt and pepper to taste. Top with green onions.