Perfect polenta can be made in the electric pressure cooker. Please note: this is not a quick-cooking recipe. From start to finish, the polenta takes about 45 minutes.
Combine water, polenta, and salt in the insert pot of an electric pressure cooker. Whisk to combine.
Lock lid in place. Set valve to sealing. Select "manual" (high pressure) and set cook time for 20 minutes.
When cooking time completes, allow pressure to release naturally, about 15 minutes. Turn sealing valve to release any remaining pressure. Gently lift the pressure cooker a few inches off the counter by one of the handles and set back down a few times. This removes any steam bubbles that could build up during cooking. Remove lid. Whisk polenta until smooth. Add butter and cheese, if desired.