Split pea soup won't soften. Any way to soften the peas without burning? I am trying to make split pea soup.  The first time I did it the peas softened just fine but the soup was scorched.  I am trying again but at a lower heat, and the peas are refusing to soften.

Ingredients are 1 bag each of split peas, frozen carrots, and frozen onions, plus a small amount of Spike seasoning.

How can I soften the peas without scorching the soup?  Is a slow cooker the best option?
Starting with more water than you think you need, keeping the lid on for a bit and then stirring a lot while it reduces to the desired consistency should be all you need to do. Don't go far from it once it starts to thicken because it will need too much stirring. 

You can cook split peas in a slow cooker, but I haven't found the softening very reliable. A fast boil before you start might help.