To same skillet, add remaining 1 tablespoon oil and the butter. Add onions and mushrooms; cook over medium-high heat about 7 minutes, stirring frequently, until tender. Stir in garlic; cook 1 minute longer. Stir in wine; cook 4 to 5 minutes, stirring occasionally, until wine is reduced by half (about 6 tablespoons). Stir in whipping cream, parsley, salt, pepper and chicken. Reduce heat; simmer uncovered about 5 minutes, stirring occasionally, until mixture is thick and creamy.