Mushroom and Fennel Pierogi Filling

Yield: Fills about 65 pierogi (8 grams each)

• 1 medium bulb fennel, diced
• 3 tsp kosher salt, divided
• 3 tbsp sunflower oil, plus more as needed (or other neutral high-heat oil)
• 1 pound crimini mushrooms, finely chopped
• 1 leek, white and light green parts only, finely chopped
• 1/4 teaspoon freshly grated nutmeg

1. Preheat oven to 400°F.
2. Toss the diced fennel with 1 teaspoon kosher salt and enough oil to cover completely. Spread evenly over a half-sheet pan and transfer to oven. Check every 15 minutes until deeply caramelized and charred in some spots.
3. Meanwhile, heat 3 tablespoons oil in large skillet. Add mushrooms, leeks, 2 teaspoons kosher salt and nutmeg. Stir frequently until the liquids begin to evaporate and the mushrooms and leeks begin to caramelize.
4. Once the mushroom mixture has become dry, transfer to a medium bowl.
5. Add the roasted fennel and mix well.