Take a stainless steel container or any instant pot safe dish for pip(pot in pot) cooking, add pasta, salt and water in the main instant pot inner pot just until pasta is underwater and to the other pip container add sauce ingredients i.e quartered tomatoes, peeled garlic cloves, and cashews. Use a trivet to put the pip dish on top of pasta inside the Instant Pot inner pot.
Now close the instant pot lid properly and seal the vent. Cook on Manual mode 4 mins high pressure for al dente pasta ( or if you are using a different kind of pasta use the thumb rule for cooking pasta in instant pot i.e Manual cook time on high pressure = Half of the time given on the package -1)
Once the Instant pot is off, wait for 5 mins and do a quick release.( Don't wait for longer than 5 mins to do a quick release as pasta gets really soft).
Let the sauce ingredients cool a little bit and blend them into a smooth puree. (If you can't wait, then add a few ice cubes or little icy cold water to blend them to avoid any heat damage to your blender)
Discard any extra water in the inner pot after cooking the pasta and put it back in the instant pot and turn on the saute mode.
Add 1 ½ tsp olive oil to the pasta in the inner pot, add the blended sauce and any preferred veggies( should be quick cooking like mushrooms or bell peppers or frozen mix veg small cut, etc.) into the inner pot. If you want to add any cooked shrimp you can add it at this point too. Skip shrimp if making a vegan version.
Add salt and pepper to taste, ¼ tsp dry basil or ¼ cup of fresh basil leaves to taste, and 1 tsp sugar. ( don't forget that you already salted your pasta).
Cook for 3 to 4 mins while stirring in between. Add ¼ tsp of paprika now. You can add little water if required to make sure the sauce doesn't get too thick before the veggies are cooked.
Mix well and check the taste to see if it needs any more seasonings and if the veggies are cooked properly and turn off the saute mode. Creamy cashew tomato pasta is ready to serve. You can serve it with little parmesan and red chilli flakes sprinkled on top if you prefer.