Ingredients

  • 1 tablespoon unsalted butter
  • 2 small heads fennel, finely chopped (about 3 cups)
  • 1/2 medium yellow onion, finely chopped
  • 2 medium carrots, peeled and finely chopped (about 2/3 cup)
  • 12 ounces white button mushrooms, sliced (about 5 cups)
  • 1 small russet potato, peeled and diced small (about 2 1/2 cups)
  • 1/4 cup all-purpose flour
  • 1 cup low-sodium mushroom broth
  • 1 cup whole milk
  • 1 cup frozen baby green peas
  • 1/4 cup thinly sliced fresh chives
  • 1/4 cup parsley
  • 1 tablespoon white vinegar
  • 1 large egg yolk
  • 7 ounces store-bought puff pastry or pie dough, defrosted if frozen

Method

  • Heat the oven to 400 degrees F and arrange a rack in the middle.
  • Melt butter over medium heat in a 3- to 4-quart Dutch oven or heavy bottomed saucepan.
  • When it foams, add fennel, onions, and carrots, and cook until just soft and onions are translucent, about 2 minutes.
  • Add mushrooms and potato, season well with salt and freshly ground black pepper, and stir to coat.
  • Cook, stirring rarely, until mushrooms have let off water and are shrunken, about 6 minutes.
  • Sprinkle flour over vegetables, stir to coat, and cook until raw flavor is gone, about 1 to 2 minutes.
  • Carefully add broth and milk, stirring constantly until mixture is smooth.
  • Bring to a simmer over medium heat and cook until slightly thickened, about 5 minutes.
  • Remove from heat, add peas, herbs, and vinegar, and stir to coat.
  • Season well with salt and freshly ground black pepper.
  • Turn filling into an 8 by 8-inch baking dish.
  • Whisk egg together with 2 teaspoons water and a pinch of salt until evenly mixed.
  • Set aside.
  • With kitchen shears, cut dough to fit over the baking dish.
  • Place dough over filling and tuck into the edges of the dish.
  • Brush dough with egg wash and cut slits in the top to vent.
  • Place on a baking sheet and bake until crust is golden brown and mixture is bubbling, about 25 to 30 minutes.
  • Let sit at least 5 minutes before serving.