Heat oven to 375°F Spray cookie sheet with cooking spray.
In large bowl, beat cake mix, 3/4 cup peanut butter, the water, vanilla and eggs on medium speed about 2 minutes or until blended. Gently stir in chocolate chips. Onto cookie sheet, drop dough by rounded teaspoonfuls about 2 inches apart.
Bake 7 to 9 minutes or until set. Cool 1 minute; remove from cookie sheet to cooling rack. Cool completely, about 10 minutes.
In medium bowl, stir together frosting ingredients. Frost cookies with frosting.