Heat oil in a small pot. Saute celery, carrots and onions for about 5 minutes. Add your spices ( basil, oregano, bay leaf, salt and pepper) tomatoes and chicken broth. Continue to simmer until carrots are tender.
In a separate pot, melt your butter. Add flour and whisk for a few minutes to create a roux. Transfer your vegetable mixture from your pot to a blender or use an immersion blender to dice up your veggies. (If you like your soup chunkier than just leave it in the pot).
Once blended to desired consistency, put half of soup mixture into roux. Simmer until thickened and add to the rest of your soup mixture. Add parmesan cheese and warmed milk, whisk to blend. Simmer over low heat for about 30 minutes or until spices and flavors have blended.