8ounceswhite button mushroomswashed, trimmed and roughly chopped
1shallotpeeled and roughly chopped
2teaspoonsfresh thyme leaves
Salt and freshly ground black pepper
Remove the filets from the refrigerator and set aside to come to room temperature.
Prepare the duxelles by placing the mushrooms, shallot, garlic and thyme in the work bowl of a food processor. Pulse until the mixture is finely chopped.
Heat the butter and olive oil in frying pan over medium heat. Add the mushroom mixture and cook until lightly browned and any liquid the mushrooms have given off has completely evaporated. Season to taste with salt and freshly ground pepper and set aside to cool.
Preheat the oven to 425°F and line a rimmed baking sheet with parchment.
Season the filets generously on both sides with salt and pepper. Heat the olive oil in a frying pan over medium-high heat.
Add the filets and sear them for 1 minute per side. Turn each filet on its side and sear just long enough to lightly brown the edges, 1 minute longer. Transfer filets to a plate and allow to cool for 5 minutes
Top each filet with a portion of duxelles and smooth the mushrooms to the edges.
On a lightly floured surface, roll the pasty dough into a 10-inch square.
Cut the pastry into quarters and center one pastry square on top of each filet. Carefully turn the filets upside down and gently stretch the pastry around the meat so it covers the bottom. Pinch the dough together as needed to completely seal the filet inside.
Place the pastry-wrapped bundles right side up on the baking sheet. Brush with the beaten egg and place in the oven.
Bake until the pastry is golden brown and an instant-read thermometer inserted in the center of the meat registers 120°F to 125°F for rare, about 12 to 16 minutes. Allow an extra 1-1/2 to 2 minutes for medium-rare (130°F to 135°F).
Allow the Wellingtons to rest for 10 minutes before serving.
Tips for Making This Recipe
For best results, ask your butcher for filets cut from the center portion of the whole beef tenderloin.