Mushroom Soup en Croûte
Puff pastry is formed by folding dough repeatedly to create layers with butter between each one. As the dough bakes, the moisture in the butter creates steam, causing the pastry to puff up. Puff pastry is easy to work withjust keep it cold so the butter stays firm. An egg wash brushed on top of the dough before baking produces a shiny, golden brown crust.
- 14 oz. frozen puff pastry, thawed
- 5 Tbs. unsalted butter
- 1 1/2 lb. cremini mushrooms, brushed clean
- 2 large shallots, minced
- 1 tsp. kosher salt, plus more, to taste
- 1/8 tsp. freshly ground pepper, plus more, to
- 3 Tbs. all-purpose flour
- 2 cups milk, warmed, plus more as needed
- 2 cups chicken stock, warmed
- 1 egg, lightly beaten
On a floured surface, roll out the puff pastry into a rectangle about 15 by 10 inches and 1/8 inch thick. Cut the pastry into six 5-inch squares. Transfer to the prepared baking sheet and refrigerate until ready to use.
In a large pot over medium heat, melt 2 Tbs. of the butter. Add the mushrooms and shallots and cook, stirring, for 1 minute. Reduce the heat to low, cover and cook until the mushrooms are soft, 5 to 7 minutes. Uncover, increase the heat to medium-high and cook, stirring, until the liquid evaporates, 3 to 5 minutes more. Stir in the 1 tsp. salt and the 1/8 tsp. pepper. Transfer the mushrooms to a food processor and pulse until finely chopped. Set aside.
In the same pot over medium-low heat, melt the remaining 3 Tbs. butter. Sprinkle in the flour and stir until no lumps are visible. Slowly whisk in the 2 cups milk until combined. Cook, stirring with a wooden spoon, until the mixture is bubbling vigorously and thickened. While stirring, slowly add the stock. Bring to a gentle simmer and cook, stirring, for 3 minutes more. The mixture should be opaque and beige in color. Stir in the mushroom puree. Season with salt and pepper and thin with additional milk, if needed. Ladle the soup into 6 ovenproof bowls and place on a baking sheet.
Brush the tops of the puff pastry squares with the beaten egg. Place 1 square on top of each bowl and press the edges to adhere. Bake until the pastry is puffed and golden, 15 to 20 minutes. Serve immediately. Serves 6.