Melt 1 tablespoon butter in 12-inch nonstick skillet over medium heat until hot. Add shallots, cook 2 minutes until golden brown, stirring often. Add mushrooms and garlic; cook for 3 to 4 minutes until mushrooms are tender, stirring often.
Stir in wine; simmer 7 to 8 minutes. Add broth and bring to a boil; simmer 15 to 20 minutes until the liquid has reduced by half. Whisk in remaining 2 tablespoons butter; stirring until the butter is incorporated. Stir in tarragon leaves. Season with salt and pepper, as desired.
Nutrition information per serving: 31 Calories; 16.2 Calories from fat; 1.8g Total Fat (1.1 g Saturated Fat; 0.1 g Trans Fat; 0.1 g Polyunsaturated Fat; 0.5 g Monounsaturated Fat;) 4.6 mg Cholesterol; 45 mg Sodium; 1.3 g Total Carbohydrate; 0.2 g Dietary Fiber; 0.7 g Protein; 0.1 mg Iron; 59 mg Potassium; 0.5 mg NE Niacin; 0.1 mg Vitamin B6; 0 mcg Vitamin B12; 0.1 mg Zinc; 1.2 mcg Selenium; 3.8 mg Choline.