Preheat oven to 350 degrees F. Lightly coat two cookie sheets with cooking spray; set aside. In a large bowl, stir together banana, peanut butter, honey, and vanilla. In a small bowl, combine oats, flour, milk powder, cinnamon, and baking soda. Stir the oat mixture into the banana mixture until combined. Stir in dried cranberries.
Using a 1/4-cup measure, drop mounds of dough 3 inches apart on prepared baking sheets. With a thin metal or small plastic spatula dipped in water, flatten and spread each mound of dough to a 2 3/4-inch round, about 1/2-inch thick. Once baked, each cookie will be about 3-1/2 to 4 inches in diameter.
Bake, one sheet at a time, for 14 to 16 minutes or until browned. Transfer to wire racks to cool completely. Store in an airtight container or resealable plastic bag for up to 3 days or freeze for up to 2 months; thaw before serving.