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A bowl of tomato soup that was made in the slow cooker with parmesan cheese and sliced basil.

Slow Cooker Tomato Soup

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  • Author: Kelli Avila
  • Prep Time: 00:05
  • Cook Time: 06:00
  • Total Time: 6 hours 5 minutes
  • Yield: Serves 6
  • Category: Soup
  • Method: Slow Cooker


A creamy and nostalgic childhood favorite, this Slow Cooker Tomato Soup cooks gently all day, filling your home with the most amazing scent that makes your family eager for dinner time. This creamy tomato soup is made with just a few ingredients but has a well-rounded robust flavor.


Units Scale

For Tomato Soup:

  • 1 (28-ounce) can whole peeled san marzano tomatoes
  • 1 (28-ounce) can crushed san marzano tomatoes
  • 1 onion, peeled, but left whole
  • 4 tablespoons unsalted butter
  • 2 tablespoon sugar
  • 2 teaspoons coarse kosher salt, more as needed (see note)
  • 2 teaspoons garlic powder
  • 2 teaspoons dried oregano
  • 1 cup chicken or veggie broth, or more if needed
  • 1/4 cup heavy cream

For Serving:

  • Fresh basil
  • Parmesan cheese


  1. Add all ingredients, except for the heavy cream, to a large slow cooker and cook on high for 4-6 hours or low for 6-8 hours.
  2. Once done, remove the onion and discard.
  3. Using an immersion blender, blend the soup until smooth.
  4. Stir in the heavy cream. Taste and adjust the seasoning, adding more salt when necessary.
  5. Serve with fresh basil and parmesan cheese, if desired.


This recipe was tested using Diamond Crystal coarse kosher salt. If you use Morton's kosher salt or fine salt, decrease the volume by half.

Why specifically San Marzano tomatoes? Simply because they offer the best flavor for this simple tomato soup using canned tomatoes. Most grocery stores will sell canned San Marzano, so be sure to grab them if you can to use in this recipe.

This recipe was inspired by Marcella Hazan. Recipe originally published in 2022, but updated with fresh photos in 2024.