Preheat oven to 375⁰F (190⁰C).
Cream the butter and sugar until fluffy. Add eggs until mixed, then add vanilla.
Stir flour, cinnamon, nutmeg, baking soda, salt and oats together. Add to creamed mixture. Fold in rhubarb, chocolate chips and walnuts (dough will be thick).
Shape dough into 1 1/2″ balls and flatten onto prepared cookie sheets.
Bake 12-14 minutes.
Yield: 4-5 dozen large cookies
*This cookie freezes well.