Holiday Mushroom & Leek Soup

For a lot of us, the holiday season evokes many memories. I love looking back at the traditions we had as a family when I was growing up, and it’s fun to recognize how they evolved into traditions incorporated in our celebrations today.

Food was always central to it all. My mother began making cookies as soon as the calendar flipped to December – storing them in tins and boxes, hiding them from us until it got closer to Christmas, just to make sure there would be plenty for family, friends and neighbors to who might drop in – and, of course, for my sister and me. And the dinners! Early on, there were four generations of us gathered around the table to enjoy all the special foods, Italian traditions blended with American ones, creating forever-bonds and so many of the food memories I frequently mention. Those holiday dinners were served in “courses” and I can remember antipasto, salad, lasagna with assorted meats long-simmered in a rich tomato sauce, the stuffed turkey will side dishes galore and, finally, pies, roasted chestnuts and fruit. How we ate all that will forever remain a mystery! Somewhere I know I have a photo that looks an awful lot like this one that I found on the internet – it really makes me smile!

Once it came time for me to make Thanksgiving dinner myself, I carried that tradition of serving “courses” with me. It just seems to mark the meal as special, even though the days of those large gatherings have long since passed as have some of the courses! But I do prepare soup, salad, turkey with sides, and a couple of pies. Oh, and yes, sometimes roasted chestnuts even make it to the menu. You’ll be reading this just after Thanksgiving, but this Mushroom and Leek Soup is one of my favorites, and I made it for this year’s meal. This is not a difficult recipe at all, so there’s nothing to say it can’t be served any time!

I like this soup because, although I use a bit of savory whipped cream for garnish, it’s not a cream soup in and of itself – just a nice hearty broth where the mushrooms are front and center, that keeps really well for a few days in the refrigerator. For a more “every day” version, I tend to skip the cream altogether, but it does “posh it up” for the holiday. 

This recipe makes 6-8 servings. If you are serving this as part of a larger meal, you will get eight servings. If served on its own, plan on six servings.           

Mushroom & Leek Soup

Scroll down for a printable version of this recipe

Yields: 6-8 servings 

Prep time: 30 minutes (includes preparing thyme-scented whipped cream garnish)

Cook time: 45 minutes

Total time: 1 hour, 15 minutes

For the thyme-scented whipped cream garnish:

1/2 cup heavy cream

2 teaspoons chopped fresh thyme

For the soup:

6 Tablespoons (3/4 stick) unsalted butter, divided into a 4 T portion & a 2 T portion

2 lbs cremini (also known as “baby bella”) mushrooms, wiped clean with a damp towel

2-3 large leeks, white and pale green parts only

6 Tablespoons all-purpose flour

6 cups chicken broth or stock (feel free to substitute vegetable broth for a vegetarian version)

1 teaspoon chopped fresh thyme

1 teaspoon salt

3/4 teaspoon pepper

First, let’s make the thyme-scented whipped cream garnish. It may sound odd to make a savory whipped cream instead of the familiar sweetened whipped cream, but it makes for a nice addition to the soup. Soup is often served with sour cream or crème fraiche as an added garnish, but the whipped cream is a bit lighter and just melts beautifully into the soup.

Whip the cream using an electric mixer (or by hand with a whisk) just until soft peaks form. Then, using a spatula, gently fold in 2 teaspoons of chopped thyme. Set this aside in a covered bowl and refrigerate. Remove it from the refrigerator just before serving. If it separates before serving, give it a good whisk by hand until those soft peaks return.

Now onto the mushrooms. If the stem is intact, I like to leave it on, but trim the stem so it’s even with the bottom of the mushroom cap. (By “intact” I mean that it is attached completely to the bottom of the mushroom and you cannot see it under the mushroom cap at all.) Slice the mushrooms about 1/4” thick. If you find a few of those “baby bellas” are more the size of “adolescent bellas” feel free to cut them in half before slicing. Note that these will shrink considerably, so don’t make them too small. But this is soup, so you want them to fit on your spoon. I save any unused mushroom stems to chop up and put into my turkey stuffing/dressing.

For the leeks, use only the white and pale green parts, cutting them into about 1/4" pieces. These steps will make it easier.

Cut the leek in half lengthwise, all the way through the root end.

Then make three lengthwise cuts, but don’t cut through the root. This will allow the leek to stay together more easily as you slice it crosswise into pieces, as shown below.

You should end up with about 2.5 cups of chopped leeks. Once you have enough, reserve any uncut leeks for use in another recipe. They will store better and longer if they remain uncut. My leeks were really big and I ended up using only 1.5 of the leeks I had.

As a side note, let me mention that if you would like to try cooking those dark green leek tops, take a look at my Use Those Leek Tops blog. They make for a really nice side dish, addition to rice or mashed potatoes, or topping for fish.

Now let’s get cooking!

In a wide stock pot, heat 4 Tablespoons of butter over medium-high heat until hot, but not smoking. Add the sliced mushrooms. Toss to coat with the butter and cook, stirring occasionally. The mushrooms will release a lot of liquid. Let that simmer off. Allow the mushrooms to continue cooking until they are golden brown and begin to get a bit toasty around the edges. The whole process will take about 15-20 minutes. Remove the mushrooms and place in a bowl. 

Return the stock pot to the stove, lowering the heat to medium. Add the remaining 2 Tablespoons of butter. Stir in the leeks, tossing them in the butter. Reduce the heat to medium-low, cover the pot and let the leeks cook, stirring occasionally until soft, about 5 minutes. You may see a bit of color on a few pieces, but you are not looking to caramelize them.

Add the cooked mushrooms to the pot with the leeks and sprinkle with the flour, stirring until the flour is evenly distributed, as shown below. 

Stir in about two cups of the broth/stock, scraping up any brown bits on the bottom of the pan with a wooden spoon. Add the remaining broth/stock, 1 teaspoon of chopped thyme, salt and pepper. Bring to a boil, stirring often to make sure nothing is sticking to the bottom of the pot. Reduce the heat to low, set the lid ajar, and simmer for 20 minutes. Taste for salt and pepper, adjusting to taste. 

At this point, the soup is ready to serve or may be cooled to room temperature and refrigerated for up to two days.

When ready to serve, ladle the soup into bowls. Remove the thyme-scented whipped cream from the refrigerator and place it in a small bowl, with a grinding or two of pepper over the top. Since the cream is so light and melts into the soup so quickly, I like to I like to let my guests spoon a bit onto their soup themselves so the whipped cream isn’t melted by the time the soup gets to the table. Ladle the soup into bowls and allow your guests to top each portion with a dollop of the whipped cream.

I hope you enjoy this soup as much as I do!

Holiday or not, there’s nothing like good soup to warm your bones in Winter! The Chopping Block has two great soup-focused classes coming up in December. Don't miss Hands-On Global Soups and Stews this Sunday, December 1 at 11am, and also our Hands-On Ramen Workshop on Saturday, December 28 at 11:30am.