Preheat oven to 350.
Grind oatmeal in food processor or blender until it is fine.
In a large mixing bowl, mash banana with fork.
Mix banana and peanut butter until smooth.
Add in oatmeal, reserving 1 tablespoon. Mix well.
Dust surface with reserved ground oatmeal. Roll dough out to about ¼ inch.
Cut desired shapes for the doggie treats.
Place cutouts on parchment paper lined cookie sheet.
Bake about 15 minutes or until edges brown.
Allow to cool.
While baking: Mix cornstarch, water, honey, and food coloring to make icing.
Drizzle or apply icing with pastry brush on cooled dog treats.
Store cookies in air tight container in refrigerator.