Dump the butter, sugar, egg and bananas into a blender or a food processor and blend, scraping down the sides a couple of times, until the mixture is smooth. Add the pecans or walnuts and process briefly - just until the nuts are chopped.
In a large bowl, combine the flour, oats, baking soda, cinnamon and nutmeg. Hand your child a wooden spoon and have her stir while you pour in the banana mixture. Depending on your child, she may need a little help getting it well mixed -the batter will be thick.
Plunk the cookie batter, by heaping teaspoons, onto an ungreased cookie sheet, about 1 ½ inches (4 cm) apart. Bake at 350°F (180°C) for 10 to 12 minutes, until lightly browned on the bottom, and firm but not crunchy.
Sorry, there is no nutrition information available for this recipe.