Add the olive oil to the Instant Pot insert and press Sauté. Heat about 30 seconds.
Add the diced onion, shredded carrots, garlic (if using), and dried basil. Sauté 4-5 minutes until softened and lightly browned.
Pour in the broth and scrape the bottom of the pot well to release any browned bits.
Add the crushed tomatoes and stir. Stir in the heavy cream.
Lock the lid, set the valve to Sealing, and pressure cook on High for 5 minutes.
Allow a full natural pressure release, about 15-20 minutes. Never force the lid.
Blend with an immersion blender until completely smooth.
Season with salt and pepper, stir in fresh basil, and serve.