Put peas into slow cooker, press ham down into them. Sprinkle all ingredients around ham bone, then pour water over.
Cook on LOW for 8 to 10 hours or on HIGH for 6 hours. (Alternatively, 2.5 hours on low on stove, 1 h - 1 hr 20 min in pressure cooker/Instant Pot on HIGH)
Take out ham bone, shred ham meat. Throw away bone and fatty skin.
Discard bay leaves. Use stick blender to pulse 2 or 3 times - thickens soup but doesn't make it completely smooth (my preference, you can blend completely if you want).
Put ham back into slow cooker, stir. Taste and add more salt if needed (soup gets lots of salt from ham).
Serve garnished with parsley. Serve with crusty bread for dunking - make a quick Irish Soda Bread, Garlic Bread or upgrade to Cheesy Garlic Bread!