I have hazy memories of a first date at a cozy French bistro with a bottle of red, a baguette, gooey cheese, and a satiny bowl of mushroom soup as a first course. I might not remember my date's name, but the memory of that soup remains. This recipe recreates that magic by slow cooking roasted cremini mushrooms and dried porcinis — a far cry from the creamy mushroom soup found in a familiar red-and-white can.
Cooking earthy, umami-rich mushrooms low and slow with a splash of sherry supplies a background note of nutty sweetness that only a fortified wine can provide. Slow cooker soups run the risk of singing only one note, but by incorporating two types of mushrooms, a fortified wine, fresh herbs, and a squeeze of fresh lemon juice, all of the rich, earthy nuances of the mushrooms stand out.
Double Mushroom Power
This slow cooker soup actually starts with a trip to the oven. Fresh mushrooms have a very high water content, so a quick blast in a hot oven removes much of the excess liquid while concentrating their flavor and even caramelizing them slightly.
Dried porcini mushrooms have a delightfully strong and nutty flavor. We skip the standard pre-soak, instead rehydrating porcinis in the low and slow simmer of the slow cooker. Snip them down to size with a pair of kitchen shears before stirring them into the soup. Any flavor that would have been lost in a separate soaking liquid is preserved here, enhancing store-bought vegetable broth.
This slow cooker cream of mushroom soup is an ideal make-ahead addition to your dinner party menu. The mushrooms can be roasted a few days in advance, then refrigerated. Set the soup to slow cook as you ready the rest of the meal in anticipation of your guests' arrival. It's an elegant soup, perfect as a first course for the fanciest of dinner parties, but also a simple treat for yourself on a cozy evening at home.
Vegetarian Slow Cooker Recipes Everyone Should Know
The slow cooker is a handy tool for every kind of kitchen — including ones where vegetable-driven, plant-powered, meat-free food is the order of the day. In this series we're sharing five essential vegetarian soups to make in the slow cooker.
We'll show you how to come home to a simmering pot of lentils, a better-than-the-box vegetable broth, a luxurious cream of mushroom soup, a brothy vegetable soup for chilly nights, and a classic chili that's perfect for busy weeknights or game day.
Slow Cooker Cream of Mushroom Soup
1 1/2 pounds cremini mushrooms, sliced 1/4-inch thick
4 tablespoons (1/2 stick) unsalted butter, melted
3/4 teaspoon kosher salt
1 medium yellow onion, diced
2 cloves garlic, minced
2 cups low-sodium vegetable broth
2 tablespoons dry sherry
1/4 ounce dried porcini mushrooms, cut into 1/4-inch pieces
1/2 teaspoon freshly ground black pepper
1/2 teaspoon dried thyme
1/4 teaspoon dried tarragon
2 teaspoons freshly squeezed lemon juice
Chopped fresh thyme or tarragon leaves, for serving
Arrange a rack in the middle of the oven and heat to 375°F. Place the cremini mushrooms on a rimmed baking sheet. Drizzle with the butter, sprinkle with the salt, and toss to combine. Spread into a single layer. Roast until mushrooms are tender, beginning to brown, and most of the liquid has evaporated, 15 to 17 minutes.
Transfer the roasted mushrooms and their liquid to a 3 1/2- to 4-quart slow cooker. Add the onion, garlic, broth, sherry, porcini mushrooms, pepper, thyme, and tarragon, and stir to combine. Cover and cook on the LOW setting until the soup is fragrant and the dried mushrooms are very tender, 3 to 4 hours.
Use an immersion blender, or transfer the soup in batches to a blender, and blend to desired consistency. Return to the pot if needed and cook on LOW for up to 2 additional hours. Before serving, stir in the cream and lemon juice. Ladle into bowls and garnish with an extra swirl of heavy cream and fresh chopped thyme or tarragon.
Make ahead: The mushrooms can be roasted up to 2 days in advance. Once cooked, refrigerate in an airtight container until ready to finish the soup.
Storage: Refrigerate leftovers in an airtight container for up to 4 days.