This dish is worthy of presenting at the table, to be carved, at holiday time or any special occasion. A filling of thyme-scented mushrooms and melted Brie are revealed when the golden puff pastry is sliced. An onion cream sauce adds full flourish, worthy of a main course, although it can also be served as a side dish.
Courtesy of Anna Olson.
Onion Cream Sauce
For the Wellington, heat a large sauté pan over medium-high heat and add the oil (or butter), shallots and mushrooms. Sauté the mushrooms until they are fully cooked and any liquid has evaporated. Stir in the garlic, thyme and season lightly, cooking one minute more. Add the brandy and remove the mushrooms from the heat to cool to room temperature, and then stir in the breadcrumbs and Brie pieces.
Preheat the oven to 400ºF. Lay out the 2 puff pastry sheets on top of each other and trim off a 1 1/2-inch strip from each side and set aside. Place one sheet of pastry onto a parchment lined baking tray. Brush the edges with the egg wash and use the reserved strips to create a frame on the pastry base, trimming the strips as needed and then brushing them with the egg wash. Spoon the cooled mushroom filling into the centre of the pastry, pressing in firmly. Top the filling with the second sheet of pastry, stretching it if needed, to have it reach the edges of the base pastry.
Brush the top of the Wellington with the egg wash and cut any remaining puff pastry pieces into designs to use as décor on top, brushing them with egg as well. With scissors, snip little air vents into the top of the Wellington. Bake for 10 minutes at 400ºF and then reduce the oven to 375ºF to cook for another 35 to 40 minutes, until the pastry is a rich golden brown. Allow the Wellington to cool for 10 minutes before slicing and serving with the onion cream sauce.
For the onion cream sauce, heat a large sauté pan over medium heat and add the oil (or butter), onions and thyme. Sauté the onions, stirring often, until they caramelize, about 25 minutes. Once a rich brown colour is achieved, stir in the brandy and the cream, bringing this to a simmer. Puree the mixture until smooth and season to taste. The sauce can be prepared ahead of time and reheated.