First, preheat your oven to 425℉ (218℃).
While the oven is preheating, chop up your tomatoes and onions. Cherry tomatoes can be halved, the larger tomatoes quartered, and onions cut in half and then quartered. Transfer the chopped vegetables to a 3x18in (33x45.5cm) baking tray (bonus points if you use a silpat to keep everything from sticking to the pan). Drizzle with olive oil, salt, and pepper then give them a toss to coat.
For the 4 cloves of roasted garlic, cut the top off a garlic bulb so the tops of each clove have been sliced off. Then place the bulb onto the middle of a piece of aluminum foil, drizzle about 1tbsp (15ml or 11g) of olive oil over the top, and wrap up the whole thing so it won't leak. Set the foil packet on the pan with the tomatoes and onions. Place everything in the oven to bake for 40 minutes.
While the tomatoes, onions, and garlic are cooking, put all of the other ingredients, EXCEPT for the parmesan, into a blender and set aside.
After 40 minutes, take the baking tray out of the oven and scoop the cooked veggies and squeeze out the needed roasted cloves into the blender (no judement here if more than 4 end up in the bisque) with everything else. Blend until smooth. You may need to blend in two batches depending on the size of your blender.
Pour the blended soup into a pot and place it on the stove. Turn the heat to medium-low and add in the parmesan rind. Let the soup simmer for 30-60 minutes, to mellow down the herbs and really marry all of the flavors.
Ladle the soup into bowls and top with croutons, basil oil, and/or more cream.