Prepare ROYAL ICING and place in pastry bag with small tip. Remove wrappers from candies.
Place mini vanilla wafer cookies on tray or plate with flat side of cookie towards the top. Squeeze small amount of icing onto bottom of candy piece. Immediately press candy bottom onto vanilla wafer cookie. Allow icing to set.
Place small dab of icing on bottom of peanut butter chip or butterscotch chip; immediately attach to top of cookie to finish acorn.
ROYAL ICING: Stir together 1/2 cup plus 1 tablespoon powdered sugar, 1-1/2 teaspoons warm water and 3/4 teaspoon pasteurized dried egg whites (meringue powder). Beat until spreadable. Add additional water, 1/2 teaspoon at a time, to get desired consistency. Tint with food color, if desired. Cover icing with damp paper towel to keep icing from drying out. About 1/4 cup icing.