Place all ingredients except the fresh basil into the slow cooker. Stir together.
Cook in standard Slow Cooker for approx 4 hours on High (using a basic crock-pot low vs high options) or 6+ hours on LOW. (If using the Instant Pot slow-cooker function, cook for 4 hours.)
If using an Instant Pot or other electric pressure cooker, choose Manual High Pressure and set for 3 minutes. Allow natural release for 10 minutes.
Before serving remove 1 cup of mixture and mash with a fork. Return mashed portion to crockpot and add chopped fresh basil.
Serve over a bed of rice and sprinkle with roasted cashews if desired.