Turn the Instant Pot to sauté mode. Add 1 teaspoon butter, 1 teaspoon olive oil, diced 1 large onion , grated 2 medium carrots and minced 3 cloves garlic. Cook until softened and fragrant, about 5 minutes.
Stir in the 3 tablespoons Tomato paste and cook for 2 minutes to deepen the flavor.
Add 56 ounces whole tomatoes (with juices) and 4 cups vegetable broth or chicken broth. Stir to combine.
Close the Instant Pot lid and set the valve to sealing. Cook on high pressure for 8 minutes.
Once done, carefully perform a quick release to remove remaining pressure.
Use an immersion blender to blend the soup until creamy and smooth.
Stir in 1 cup heavy cream 1 teaspoon basil,1 1/2 teaspoons salt , and 1 teaspoon black pepper . Adjust seasoning to taste.
Ladle soup into bowls and garnish with fresh basil or a swirl of cream if desired.