Condensed Cream of Mushroom Soup made with Sourdough Starter

Name: Condensed Cream of Mushroom Soup made with Sourdough Starter
Prep time: 5 min
Cook time: 10 min
Total time: 15 min
Ingredients: 1/4 cup unfed sourdough discard (see notes for using active sourdough starter); 1 cup mushrooms (finely chopped, about 3 oz); 2 tablespoons butter; 1/2 cup chicken broth (sub vegetable broth); 1/3 cup whole milk; 1/2 teaspoon garlic powder; 1/2 teaspoon onion powder; 1/8 teaspoon celery seed; 1/4 teaspoon salt; 1/4 teaspoon black pepper

This homemade Condensed Cream of Mushroom Soup recipe, made with sourdough starter, is rich, creamy, and full of earthy mushroom flavor.

It takes just 15 minutes to make and is a great way to use your sourdough discard for soups, casseroles, slow-cooked dishes, and more!

A jar of condensed cream of mushroom soup with a spoon.

Homemade cream of mushroom soup is quick and easy to make, and a great way to put that extra sourdough discard to use. Whether you’ve got discard or active starter, both work perfectly in this recipe.

This version brings out a deep, savory mushroom flavor that takes casseroles, sauces, or even a simple bowl of soup to the next level. The sourdough starter adds a velvety thickness and a hint of tang that makes it stand out from the canned stuff. Plus, it’s made with wholesome, fresh ingredients, so you can feel good about every spoonful!

Just like our condensed cream of chicken soup made with sourdough starter, this is a recipe you'll want to save for the holidays!

Ingredients & Substitutions

Cream of mushroom soup ingredients on a table.

mushrooms: Cremini mushrooms, baby bella mushrooms, shiitake mushrooms, and button mushrooms are all great options for this soup.
sourdough starter & butter: While flour is traditionally used in cream of mushroom soup, sourdough discard is a fantastic alternative that adds a slight tang and boosts the flavor. The butter and sourdough starter form the base of the roux, which helps thicken the soup.
chicken broth & milk: The chicken broth brings the savory chicken flavor, while the milk adds that creamy texture. I highly recommend making your own chicken broth for the best flavor, but store-bought works just fine if that's what you have. You can swap the milk for heavy cream to add a richer flavor.
seasonings: Garlic powder, onion powder, celery seed, salt, and black pepper are the key seasonings that give this soup its classic taste.
vegan and vegetarian options: You can easily make this soup dairy-free by using plant-based butter and milk, along with vegetable stock/broth or water, and a vegan chicken bouillon powder.

How to make Condensed Cream of Mushroom Soup made with Sourdough Starter

Cooking mushrooms with butter in a saucepan.

Step 1: Melt the butter and cook the mushrooms.

Melt the butter over medium heat in a medium pot.

Add the mushrooms and cook until they have released most of their liquid, about 5-6 minutes.

Whisking the sourdough starter in with the mushrooms and butter in a saucepan.

Step 2: Add the seasonings and sourdough starter.

Add the seasonings and sourdough starter to the pan and whisk continuously until it thickens. This will take about 30-60 seconds.

Adding milk and broth to cream of mushroom soup in a saucepan.

Step 3: Add the broth and milk.

Whisk in the broth, a tablespoon at a time, to break up any lumps. Then add the milk.

Step 4: Thicken

Keep whisking continuously for 2-3 minutes until the soup thickens.

Pro Tip

To avoid lumps in the soup base, slowly whisk in the broth a few tablespoons at a time into the thick butter, mushroom and sourdough mixture.

This gradual process helps create a smooth, creamy texture, ideal for your homemade cream of mushroom soup.

How to Store

Fridge: Store the soup in a mason jar with a tight-fitting lid or an airtight container, and refrigerate it for 5-7 days.

Freezing: We tested freezing and thawing the soup. While the texture became slightly grainier than fresh, it blended well when liquid was added to make a soup. It's still great for casseroles, though the texture might not be as smooth as freshly made.

To freeze, use a mason jar with a tight-fitting lid or an airtight container, and store it in the freezer for up to 1 month.

How to use

If you want to make a cream of mushroom soup, after you've made the condensed cream of mushroom soup, add 3 cups of chicken broth or vegetable broth to the saucepan and whisk until it is smooth with no lumps.

Thinning cream of mushroom soup with broth in a saucepan.

This will make 4 (1) cup servings. Serve immediately topped with fresh herbs such as fresh thyme, chives, rosemary tarragon, or parsley.

How can I thicken my cream of mushroom soup?

If your cream of mushroom soup is too thin, make a slurry by mixing flour and water, then add it to the soup. Simmer and whisk until the soup thickens. You also make a cornstarch slurry.

more easy soup recipes

Carrot Ginger Soup

Creamy Chicken Potato Soup

Loaded Potato Soup made with Sourdough Starter

Condensed Cream of Chicken Soup made with Sourdough Starter

- SUBSCRIBE -

Do you like this recipe?

Subscribe to our newsletter and we'll send you more fresh recipes, valuable troubleshooting advice, useful tips, and other information we believe will be helpful to you!