Heat oven to 375°F (350°F for dark or nonstick cookie sheets). In large bowl, beat half of the cake mix, the water, peanut butter, butter and eggs with electric mixer on medium speed until smooth, or mix with spoon. Stir in remaining cake mix.
On ungreased cookie sheet, drop dough by rounded tablespoonfuls about 2 inches apart. Flatten in crisscross pattern with fork dipped in sugar.
Bake 9 to 11 minutes or until golden brown. Cool 1 minute; remove from cookie sheet to cooling rack. Store covered.