Published: Aug 30, 2022 · Modified: Sep 6, 2024 by Carolyn

Roasted Tomato Soup

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This keto tomato soup tastes like summer in a bowl! It’s incredibly thick and creamy, with deep roasted tomato flavor, accented by fresh basil and Parmesan. It’s a delicious low carb way to use your summer produce.

Close up shot of a bowl of Roasted Tomato Soup with basil and Parmesan.

This is hands-down the BEST keto tomato soup I have ever made. And I’ve made a lot of it in my decade plus of following a low carb diet.

It’s a recipe I developed last summer when I had an over-abundance of tomatoes. I threw it together without measuring, as I am wont to do when cooking for my family. I had a pan full of roasted tomatoes and I tossed in some other ingredients and let it simmer.

The minute I tasted the velvety rich flavor, I knew I had a winner on my hands. I had to make it several times to re-create the magic of that first batch. But once I nailed this roasted tomato soup recipe, I wrote it all down so I could share it with you.

And it goes so well with my Easy Keto Biscuits, too!

Top down image of a large blue dutch oven filled with keto tomato soup, with basil leaves floating on top.

Why you will love this soup

This isn’t any old keto tomato soup. It’s a bit of a jazzed up version. Or perhaps I should say it’s a “souped up” version. It has added ingredients that punch up the tastiness and make it creamier. All while keeping it lower in carbs than the conventional kind.

For one thing, it uses roasted tomatoes rather than fresh. Cooking tomatoes in a high heat oven causes them to caramelize slightly, intensifying their natural flavor. Even tomatoes that aren’t quite ripe can benefit from roasting.

Then you add fresh summer basil and grated Parmesan, both of which complement tomatoes perfectly. I used a similar combination in my delectable Tomato Basil Chicken.

But this roasted tomato soup also has a secret ingredient: zucchini! Adding some fresh zucchini makes it thicker than most keto soup recipes, without any funny additives or special ingredients. You don’t taste the zucchini at all, but it helps the consistency and ups the nutrition too!

Ingredients you need

Fresh tomatoes, basil, and parmesan on a small wooden cutting board.

Tomatoes: Try to pick tomatoes that are at the peak of freshness, with firm flesh and a deep red color. But as I said above, even under-ripe tomatoes benefit from roasting.
Garlic: Fresh garlic is preferable over garlic powder.
Zucchini: You won’t taste the added zucchini, I promise. But it adds body and thickness so I don’t recommend skipping it.
Basil: Tomatoes and basil go together like peanut butter and jelly! Use fresh basil rather than dried.
Whipping cream: Make it extra creamy by stirring in some heavy whipping cream at the end.
Parmesan: Freshly grated Parmesan takes this soup from really great to absolutely fabulous! I don’t recommend the powdered kind that comes in a green can, as it’s simply not the same.
Pantry staples: Chicken broth, olive oil, salt, pepper

Step by Step Directions

A collage of 4 images showing the steps for making Keto Tomato Soup.

1. Roast the tomatoes: Spread the tomatoes in a baking dish and drizzle with oil. Sprinkle with salt and pepper, and roast for 30 minutes at 400ºF, until caramelized.

2. Simmer the vegetables: Sauté the garlic and zucchini in a little more oil, then stir in the tomatoes and chicken broth. Bring to a simmer and cook 10 minutes, until the zucchini is tender.

3. Blend the soup: Add the basil leaves and let wilt a few minutes. Then transfer the soup to a large blender or food processor and puree. You may need to work in batches to accommodate all the soup. You can also use an immersion blender, and blend right in the pot.

4. Return to the pot: Return the soup to the pot and stir in the heavy cream. Add the Parmesan cheese and stir until melted and combined. Taste the soup and adjust seasonings as desired.

A black bowl filled with creamy Keto Tomato Soup, topped with parmesan and basil.

Expert Tips

Freezing Roasted Tomatoes: If you find yourself drowning in summer tomatoes, roast them and freeze them for later use. I do this every year. I store them in unsealed pint jars until they are frozen solid, and then I add the lid.

Make sure to add all the liquid from the roasting pans, as well. Don’t miss out on that added flavor! That way, you can enjoy this Roasted Tomato Soup recipe all year long.

Canned Tomatoes: Yes, you can make this soup with canned tomatoes. It won’t quite be the same but it works. I recommend using a 28 ounce can of fire roasted tomatoes. Start at Step 2 of the instructions and add the canned tomatoes and all the juices in at Step 3.

Dairy-Free Option: Use coconut cream in place of the whipping cream and dairy-free parmesan or nutritional yeast in place of the Parmesan cheese.

A bowl of keto roasted tomato soup in front of a cutting board piled with keto biscuits.

Frequently Asked Questions

Are tomatoes keto-friendly?

Tomatoes can be consumed on a keto diet, but you don’t want to over-do it. The carbs can add up quickly! That’s why this roasted tomato soup recipe includes some zucchini, to give a thicker consistency without diluting the flavor. It also adds nutrition and additional fiber.

Why is tomato soup so high in carbs?

Many store-bought soups are shockingly high in carbs and aren’t good for keto diets. They often contain added sugar and starches to make them thicker and more flavorful. However, this keto tomato soup is rich, thick, and has only 5.6g of net carbs per serving.

Why are roasted tomatoes so good?

Fresh tomatoes have a high liquid content, but roasting them causes much of the liquid to evaporate. This concentrates the flavor, as well as caramelizes the natural sugars and enhances the sweetness. Roasted tomatoes are a great way to add a flavor boost to your favorite keto dinner recipes!

Can you freeze keto tomato soup?

This delicious soup freezes very well. Store in glass jars or non-toxic plastic containers for up to 6 months. I recommend freezing them with no lid first, to allow the liquid to expand. Once frozen, add the lids to seal them.

Love keto soup recipes? Check out my cookbook!

Banner showing Keto Soups and Stews Cookbook.

Roasted Tomato Soup Recipe

This keto tomato soup tastes like summer in a bowl! It's incredibly thick and creamy, with deep roasted tomato flavor, accented by fresh basil and Parmesan. It's a delicious low carb way to use your summer produce.

4.62 from 13 votes

Print Pin Rate

Course: Soup

Cuisine: American

Keyword: keto tomato soup, roasted tomato soup

Prep Time: 20

Cook Time: 45

Servings: servings

Calories: 162kcal

Ingredients

2 lbs fresh tomatoes cored and coarsely chopped
3 tablespoon olive oil divided
¾ teaspoon kosher salt
½ teaspoon freshly ground pepper
4 cloves garlic minced
12 ounces zucchini, chopped (about 1 medium)
4 cups chicken broth low sodium
½ cup loosely packed fresh basil leaves
½ cup heavy whipping cream
2 ounces freshly grated Parmesan

US Customary – Metric

Instructions

Preheat the oven to 400ºF and spread the tomatoes in a single layer in a large glass or ceramic baking dish. Drizzle with 1 tablespoon of the oil and sprinkle with salt and pepper. Bake 30 minutes, until tomatoes have caramelized.
In a large saucepan, heat the remaining 2 tablespoons of oil over medium heat. Add the garlic and sauté until fragrant, about 1 minute. Then add the zucchini and sauté 2 minutes.
Stir in the tomatoes and any accumulated juices from the baking dish. Add the chicken broth and bring to a simmer. Reduce the heat and simmer 10 minutes, until the zucchini is tender.
Add the basil leaves and let wilt. Then transfer to a large blender or food processor, or use an immersion blender, and blend until smooth. You may need to work in batches if using a blender.
Return to the pot and stir in the whipping cream and Parmesan until the cheese is melted. Taste and adjust seasonings as desired.

Notes

Storage Information: Store the soup in the fridge in a covered container for up to 5 days. You can also freeze the soup for several months.

I recommend freezing them with no lid first, to allow the liquid to expand. Once frozen, add the lids to seal them.

Nutrition Facts

Roasted Tomato Soup Recipe

Amount Per Serving (1 cup)

Calories 162 Calories from Fat 109

% Daily Value*

Fat 12.1g19%

Carbohydrates 7.5g3%

Fiber 1.9g8%

Protein 6g12%

* Percent Daily Values are based on a 2000 calorie diet.

Please note that I am not a medical or nutritional professional. I am simply recounting and sharing my own experiences on this blog. Nothing I express here should be taken as medical advice and you should consult with your doctor before starting any diet or exercise program. I provide nutritional information for my recipes simply as a courtesy to my readers. It is calculated using MacGourmet software and I remove erythritol from the final carb count and net carb count, as it does not affect my own blood glucose levels. I do my best to be as accurate as possible but you should independently calculate nutritional information on your own before relying on them. I expressly disclaim any and all liability of any kind with respect to any act or omission wholly or in part in reliance on anything contained in this website.

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Comments

4.62 from 13 votes (5 ratings without comment)