Using the saute feature of your Instant Pot, saute chopped celery, onion, and carrot in olive oil until just soft, about 5 minutes. Add garlic and saute for another 1-2 minutes.
Turn off saute and switch to pressure cook mode.
Add marinara sauce, chicken broth canned tomatoes, Italian seasoning, salt & pepper. Pressure cook on high for 10 minutes.
Natural release for 5 minutes, then manual release until the pin drops.
Using an immersion blender, blend until soup is smooth.
Slowly stir in half & half
Serve with grilled cheese sandwiches or a side salad for a quick and delicious meal!!