Combine all ingredients in your pressure cooker, layering the frozen-shell-on-shrimp on the top.
Secure lid and cook under pressure (high if you have a choice) for 5 minutes.
Quickly depressurize (by turning the valve of an electric multi cooker or placing a stove top unit under cool running water)
The paella can be served with the shells on the shrimp or, If desired, gently remove cooked shrimp from the rice and peel. Add peeled shrimp back into the rice and serve. discard the shells.
Serve each serving with a garnish of fresh parsley, butter, grated cheese and squeeze of lemon juice.