1. In a saucepan, melt butter or margarine over a low flame without allowing it to brown.
2. When the butter starts to froth, add frozen shrimps.
3. Simmer the shrimp for 20 to 25 minutes, sautéing frequently, until they are tender.
4. Sprinkle lemon juice and parsley over and toss to mix.
5. Dish out into a serving bowl.
6. Serve hot and buttery accompanied with toast triangles or over rice.