In a medium saucepan, saute mushrooms in 1 teaspoon butter until tender. Stir in shrimp, and cook until pink. Transfer to a bowl.
In the same saucepan, melt the remaining 2 teaspoons butter. Slowly mix in cream. Stir in the shrimp and mushroom mixture, and season to taste with garlic powder and black pepper. Simmer over very low heat until thick. Just before serving, stir in wine.
