In a small saucepan, combine stock and wild mushrooms, and season with salt and pepper. Cook over medium heat for 30 minutes. Meanwhile, combine dried mushrooms and cream in a small saucepan. Season with salt and pepper. Cook over medium-high heat until reduced by 1/3; set aside. Add potato to stock mixture, and cook until very tender, about 15 minutes. Working in batches, transfer stock mixture to a blender with garlic and rosemary. Puree until very smooth. Slowly add reduced cream mixture, and puree until smooth. Transfer to a medium saucepan, and keep warm.
Evenly distribute spinach coulis between 8 large martini glasses. Place an egg in each glass. Cover with some of the mushroom soup. Drizzle with truffle oil. Garnish with bacon, brioche, and lovage. Serve immediately.