1. In 2-quart saucepan over medium-high heat, heat cream to boiling. Reduce heat to low; simmer, uncovered, until cream thickens and is reduced by half, about 45 minutes, stirring occasionally to prevent cream from boiling over. Remove saucepan from heat.
2. Meanwhile, shell and devein shrimp (if you like, leave tail part of shell on). Rinse shrimp with running cold water. In 12-inch skillet over high heat, heat water and 1 teaspoon salt to boiling. Add shrimp; heat to boiling. Reduce heat to low; cook 1 minute or until shrimp are tender. Drain shrimp. Wipe skillet dry.
3. In same skillet over medium heat, in hot butter or margarine, cook onion until tender. Add white wine; over high heat, heat to boiling. Cook until wine is reduced by half. Add reduced cream to skillet with mustard, hot-pepper sauce, and 1/4 teaspoon salt. Return shrimp to skillet; over medium heat, heat through. Sprinkle with chopped parsley.