Wash peaches, cut in half, and place flesh side down in an oven safe baking dish. Fill with about 1 inch of water.
Roast peaches for 1-1.5 hours at 400 degrees.
Puree roasted peaches using a food mill or a food processor. At first I was peeling off the skin and then I decided I didn't care. The food mill caught most of the skin and what did get through didn't give the puree a bad texture.
Use an ice cube tray to freeze into cubes. I used four peaches and it made twenty cubes, each one is two tablespoons.