Preheat oven to 350.
Cream together butter and sugars. Add egg. Beat in vanilla. Mix in lentil puree.
In a separate bowl combine flour, baking soda, cinnamon and salt. Gradually mix dry mixture into butter mixture.
Once completely mixed, fold in oats and chocolate chips.
Put 1 tablespoon cookie dough on greased cookie sheet, repeat with remaining dough. Bake for 10-12 minutes until slightly brown.