Rinse the peas and add to a steaming tray in a saucepan with 1/2 an inch of water in the bottom of the saucepan. You may also use the Instant Pot to steam them but I haven't tried this yet. I used a steaming tray as shown.
Bring the water to a boil and steam the peas for 10-15 minutes until tender. Drain.
Add the butter to the peas and stir to melt.
Now, you can either use a potato masher, a fork, or and immersion blender (my tool of choice) to mush the peas. Be careful if you use an immersion blender like I did. You don't want to puree it. You want it to be a mush but with definite texture as shown.
Add the cream, salt, and pepper and stir. Serve warm with fish and chips (link above).