In a large soup pot or dutch oven over medium heat add in your diced onions, carrots, celery, and olive oil to simmer, and cook until fragrant. I like to wait until the onions are translucent maybe a little brown to give even more flavor to this bisque. Right around 5-7 minutes. Then add in minced garlic to the pot and cook for a few minutes. Add in Italian seasoning and stir evenly throughout the pot. Do not burn the garlic so keep a close eye on it right now!
If you are thickening with flour, go ahead and sprinkle it over the sautéed veggie mixture now. If you are using heavy cream or milk simply add this in after you add in your tomatoes.
Add your chopped tomatoes, chicken stock, black pepper, and salt. Bring it all to a simmer. This will take roughly 15 minutes. If you are thickening with milk or cream to create your bisque now is the time to add it in.
Once all of the ingredients are added together to the pot let the flavors meld together on medium heat for about 5 more minutes. At this point, you can take your immersion blender or your countertop blender and blend the soup until it is completely smooth and creamy.
You can now ladle and serve the tomato bisque into separate bowls and garnish with fresh chopped basil, croutons, and parmesan cheese.