Preheat oven to 350 degrees.
Beat butter and sugar in a bowl or mixer until creamy. Beat in the egg. Stir in rhubarb.
Combine flour, salt, baking soda, cinnamon, nutmeg, cloves, and ginger in another bowl.
Stir dry ingredients into rhubarb mixture with wet ingredients until well mixed.
Fold in walnuts and white chocolate chips.
Place batter on a greased baking sheet.
Bake for approximately 12 minutes or until lightly browned
Cool cookies on a rack. This recipe makes approximately 2 dozen cookies.