Vegetarian Shepherd's Pie

Bahan-bahan (6 porsi)

• 1 1/2 pounds russet potatoes (peeled and cut into 1-inch chunks)
• 3 tablespoons unsalted butter (diced)
• 1/4 cup freshly grated Parmesan cheese
• 1/2 teaspoon kosher salt
• 1/4 teaspoon ground black pepper
• 1/4 cup milk (or half-and-half)
• 1 large egg yolk
• 2 tablespoons extra-virgin olive oil
• 1 yellow onion (chopped)
• 4 large carrots (scrubbed and diced)
• 2 parsnips (peeled and diced (or 2 additional carrots))
• 8 ounces baby bella (cremini) mushrooms (roughly chopped)
• 8 ounces sliced shiitake mushrooms (or more baby bella mushrooms)
• 1/2 teaspoon kosher salt
• 1/4 teaspoon ground black pepper
• 2 g arlic cloves (minced)
• 2 tablespoons tomato paste
• 2 tablespoons all-purpose flour
• 1 cup vegetable stock or broth
• 2 teaspoons low sodium soy sauce
• 2 sprigs fresh rosemary or fresh thyme
• 1 dried bay leaf
• 1 (10-ounce bag) frozen peas ((no need to thaw))