Step 1
Melt 2 Tbsp. butter in a heavy large pot over medium-high heat. Add onion and sauté until deep golden, about 7 minutes. Add potatoes, turnip, carrot, porcini mushrooms, thyme, cumin, and pepper and cook 1 minute. Add broth and 1 cup water; bring to a boil. Reduce heat, cover, and simmer until vegetables are almost tender, about 10 minutes. Stir in cream, shiitake mushrooms, peas, and chives. Season with salt. Bring mixture to a simmer. Mix flour and remaining 1 Tbsp. butter in a small bowl to blend. Stir into vegetable mixture; simmer until mixture thickens slightly, about 5 minutes. Divide vegetable mixture among six 2-cup souffle or baking dishes; set aside.
Step 2
Do Ahead: Filling can be prepared 1½ hours ahead. Let stand at room temperature.
BISCUIT TOPPING
- 2 cups all purpose flour
- 1 tablespoon baking powder
- 1 teaspoon salt
- 1/4 cup chopped fresh chives
- 6 tablespoons chilled unsalted butter, cut into 1/2-inch pieces
- 2 large eggs
- 1/2 cup whole milk
Step 3
Preheat oven to 425°. Sift 2 cups flour, baking powder, and salt into a large bowl. Stir in chives. Add butter; rub in with fingertips until mixture resembles coarse meal. Add eggs and milk and stir until soft moist dough forms.
Step 4
Turn dough out onto a generously floured surface. Knead gently just to combine. Divide dough into 6 equal pieces; pat out each piece to a 3½" round. Place 1 dough round atop vegetable filling in each dish (some filling will show around edges). Place dishes on large baking sheet. Bake until topping is golden and vegetable mixture is heated through, about 18 minutes. Let stand 5 minutes. Serve hot.
