Melt butter in skillet or wok. Stir-fry shrimp until almost done. Squeeze juice of 1 lemon over shrimp. Sprinkle ginger, onion and garlic powder over shrimp. Continue to cook until shrimp are done. Remove shrimp. Add soy sauce to the drippings.
Mix 1/2 of whipping cream and cornstarch in a separate bowl. Set aside.
Pour remaining cream into pan with drippings and cook until bubbly. Add cream and cornstarch mixture. Stir constantly until thick. Add shrimp.