Instructions

1. Preheat the oven to 350 degrees.
2. Make the mushroom duxelle by adding the butter to a large skillet over medium heat. Add the mushrooms and cook for 8-10 minutes until the have released all their moisture and have browned. Add the onion and cook another 3-4 minutes until the onion softens. Season with salt and pepper and then stir in the fresh tarragon.
3. Sprinkle the flour over the mushrooms, stir to coat and cook for 1 minute. Add the sherry and stir to deglaze the pan. Stir in the cream and then set aside to cool.
4. Add the ground beef to a large bowl along with 1/2 cup of the cooled mushroom mixture, egg plus egg yolk, salt and pepper and breadcrumbs. Mix together until combined and from into 4 oval beef patties.
5. Place one package of the crescent roll dough onto cutting board dusted with flour, press seams together and roll out slightly. Cut the dough in half down the middle so you have 2 rectangles. Add 1/4 of the mushroom mixture in the center of each rectangle and place a beef patty of top. Fold the dough over the beef patty to cover and press the seams together, if any seams start to come apart just pinch them together with your fingers. Place on a parchment lined baking sheet seam side down.
6. Repeat with the other rectangle and then use the other package of crescent roll dough to make the remaining 2 beef wellingtons.
7. Brush the tops of the dough with the egg wash and season with salt and pepper. Bake for 30 minutes, remove from the oven and let rest for 5 minutes before serving. The beef should be slightly pink, not cooked all the way through. However, if you like you beef well done then add another 5-7 minutes to the cooking time.