In a saucepan, sauté mushrooms in butter until softened. Stir in flour and ⅛ teaspoon pepper until blended. Cook for 1 minute. Gradually add the cream and tarragon. Bring to a simmer; cook and stir for 1 minute or until slightly thickened. Remove from the heat and set aside.
In a bowl, combine the egg yolk, onion, 2 tablespoons mushroom sauce, salt and pepper. Add turkey and mix well. Shape into 2 loafs. Place in the freezer for about 5 minutes to help patties firm up.
Separate crescent dough into two rectangles on a baking sheet. Seal perforations. Place 1 loaf on each. Bring edges together and pinch to seal.
Bake at 350 degrees for 26 minutes.
Meanwhile, add 2 tablespoons of half & half to the sauce and warm. Pour over Wellingtons when served.
Recipe by simple-food-solutions.com at http://simple-food-solutions.com/?p=2562