Preheat oven to 350 degrees F
In a large bowl, mix butter and sugar until soft and fluffy.
Blend in egg until smooth.
Add flour, baking soda, and oats.
Stir vigorously until all ingredients are blended
Use a tablespoon to spoon ingredients onto lightly greased baking tray making round blobs
Bake for 10-15 minutes, or until browned around the outside
Leave to cool for 10 minutes before removing from tray.