Slow Cooker Zucchini and Tomatoes

Zucchini With Tomatoes, Onions, and Peppers
Diana Rattray
  • Total: 3 hrs 15 mins
  • Prep: 15 mins
  • Cook: 3 hrs
  • Yield: 4 to 6 servings
Nutritional Guidelines (per serving)
78 Calories
3g Fat
10g Carbs
3g Protein
See Full Nutritional Guidelines Hide Full Nutritional Guidelines
Nutrition Facts
Servings: 4 to 6 servings
Amount per serving
Calories 78
% Daily Value*
Total Fat 3g 4%
Saturated Fat 2g 9%
Cholesterol 8mg 3%
Sodium 461mg 20%
Total Carbohydrate 10g 4%
Dietary Fiber 3g 10%
Protein 3g
Calcium 76mg 6%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

This simple slow cooker zucchini and tomatoes dish is a classic combination of flavors, and it's an excellent way to use a bumper crop of fresh zucchini, whether from your garden or the market. The slow cooker makes it particularly convenient when the oven and stovetop will be used for other dishes. 

The dish is made with Italian flavor combinations, and it is reminiscent of a classic ratatouille. To make a slow cooker ratatouille with this recipe, use half zucchini and half cubed eggplant (1 1/2-inch cubes). The recipe is easily scaled up and freezes well (see the tips, below).

Serve the zucchini with a chicken or fish meal, or along with steaks or chops. If you have fresh basil, use about 2 teaspoons, chopped. This easy veggie combination makes a great vegetarian topper for pasta as well. For a vegan dish, omit the butter and Parmesan cheese and use vegan Parmesan cheese or nutritional yeast. Drizzle the finished vegetables with a small amount of olive oil, if desired.


  • 1 medium onion (red or yellow)
  • 1 green bell pepper
  • 1 pound zucchini squash (about 4 medium, or summer squash)
  • 1 (14.5-ounce) can diced tomatoes (undrained, or 2 cups of crushed tomatoes)
  • 1 teaspoon kosher salt
  • 1/2 teaspoon freshly ground black pepper
  • 1/2 teaspoon dried leaf basil
  • 1 tablespoon butter
  • 1/4 cup good quality grated Parmesan cheese
  • Optional: 1 tablespoon chopped fresh parsley

Steps to Make It

  1. Gather the ingredients.

  2. Peel the onion, cut it into quarters, and slice thinly.

  3. Cut the bell pepper lengthwise; remove the stem end and seeds. Cut the pepper into strips.

  4. Slice the zucchini into rounds about 1/4-inch in thickness, or cut it into 1-inch cubes. 

  5. Combine the vegetables in the slow cooker with the tomatoes, salt, pepper, and basil.

  6. Cover the pot and cook on low for 3 hours.

  7. Dot the vegetables with butter and sprinkle with the Parmesan cheese. Cover and continue cooking on low for 1 to 1 1/2 hours.

  8. Serve garnished with fresh chopped parsley, if desired.


  • Homemade Fresh Crushed Tomatoes: Bring a large pot of water to a boil. Fill a large bowl with ice and water. Core about 1 1/2 pounds of fresh tomatoes (5 to 6, depending on size) and cut an "X" into the bottom of each one. Lower the tomatoes into the boiling water and boil for about 30 to 45 seconds. Remove them to the ice water. When the tomatoes are cool enough to handle, slip the skins off. To remove the seeds, press them through a mesh strainer or use a food mill. You should have about 2 cups of fresh crushed tomatoes.
  • For the Freezer: When the zucchini mixture has cooled slightly, ladle meal-size portions into freezer containers or freezer storage bags. Label with the name and date and freeze for up to 3 months. To reheat, thaw the vegetables in the refrigerator overnight and simmer in a saucepan on the stovetop for 10 to 20 minutes.