Beat butter & sugar until light & fluffy.
Blend in eggs & vanilla; mix well.
Add combined dry ingredients alternately with sour cream, mixing well after each addition. Stir in nuts.
Chill 4 hours or over night.
Drop rounded teaspoonfuls of dough, 3 inches apart, onto well buttered cookie sheet. (Can use parchment paper).
Bake @ 400 for 8 to 10 minutes or until lightly browned.
Cool completely prior to frosting with Burnt Butter Icing.