Heat oven to 350°F. Coat baking sheets with nonstick cooking spray.
Roll dough out with floured rolling pin on well-floured surface to 1/4-inch thickness. Using 3-3/4-inch sheep or other animal cookie cutter, cut out cookies. Place 1 inch apart on prepared baking sheets. Repeat with remaining dough.
Bake in 350°F oven 8 to 10 minutes or until lightly golden around edges. Cool cookies on baking sheet on rack 5 minutes. Remove cookies to wire rack to cool completely.
Use packaged meringue powder to prepare 1 recipe Royal Icing, following directions on package label. Or mix powdered egg whites with water. Beat in powdered sugar; beat about 6 minutes or until good spreading consistency.
Reserve 1/2 cup icing. Thin remaining icing with water, adding drop at a time, until consistency of sour cream. Tint if desired. Using small fine-tipped paint-brush, start at one edge of cookie and brush thinned icing across to opposite edge. Add a little more water if icing does not flow smoothly. Let set several hours or overnight. Tint reserved unthinned icing. Frost and decorate cookies as desired.