24 ounces cremini or portobello mushrooms, finely chopped
2 sheets frozen puff pastry, thawed
2 tablespoons olive oil
2 tablespoons unsalted butter
1 large yellow onion, diced
4 cloves garlic, minced
1 tablespoon fresh thyme, chopped
1 tablespoon fresh rosemary, chopped
1/2 cup vegetable broth mixed with 1 tablespoon balsamic vinegar
1 cup cooked lentils or finely chopped walnuts for added texture
1/2 cup breadcrumbs
1 egg, beaten for egg wash
Salt and black pepper to taste
Instructions
Heat the olive oil and butter in a large skillet over medium-high heat. Add the chopped mushrooms and cook until they release all their moisture and start to brown, which usually takes about 10 to 12 minutes. This step is crucial to prevent a soggy pastry later on.
Stir in the fresh thyme, rosemary, cooked lentils or walnuts, and breadcrumbs. Season generously with salt and pepper. Once everything is well combined, remove the skillet from the heat and let the filling cool to room temperature. If the filling is hot, it will melt the puff pastry and ruin the texture.
Preheat your oven to 400 degrees Fahrenheit. On a lightly floured surface, roll out the puff pastry sheets. Place the cooled mushroom filling in the center of the pastry, shaping it into a neat log. Fold the sides over the filling and seal the edges with a bit of water or egg wash. Place the Wellington seam-side down on a parchment-lined baking sheet.
Brush the entire surface of the pastry with the beaten egg wash for a golden finish. Use a sharp knife to gently score a pattern on top, being careful not to cut all the way through. Bake for 25 to 30 minutes, or until the pastry is puffed and deep golden brown. Let it rest for 10 minutes before slicing.
