Once the roasted tomatoes are about 5 minutes away from being done, turn on your Instant Pot and select the 'Saute' function.
Add olive oil and onions and saute to until the onions are aromatic (about 3-5 minutes).
Add garlic and continue to saute for an additional 1-2 minutes.
Once roasted tomatoes are done baking, remove from the oven and add to the Instant Pot with all the seasoning and juice from the pan.
Add fresh basil leaves (or dried basil, if needed), remaining Italian seasoning, remaining garlic pepper, salt, butter, crushed red pepper, plum tomatoes, thyme, and chicken broth (or vegetable broth, if preferred).
Secure the lid onto the Instant Pot and select the 'Pressure Cook' function on high. Cook for 8 minutes if using roasted tomatoes, 20 minutes if you're using fresh tomatoes.
Once the timer beeps, select the 'Cancel' function and allow the Instant Pot to naturally release pressure for 15-20 minutes. Once the 15 minutes has expired, quick release all remaining pressure. Carefully remove the lid.
Using an immersion blender, blend the soup until you have reached your desired consistency. NOTE: we like ours slightly chunky. It will likely only take less than a minute to blend. If needed, you can also use a blender.
Serve warm topped with grilled cheese crutons, crispy crutons and Parmesan cheese. ENJOY!