1Heat oven to 375°F (350°F for dark or nonstick cookie sheets). Make and bake chocolate chunk cookies as directed on package, using 1/2 cup butter and 1 of the eggs. Remove from cookie sheets to cooling racks; cool completely.
2Make and bake peanut butter cookies as directed on package, using oil, water and remaining 1 egg. Remove from cookie sheets to cooling racks; cool completely.
3In small bowl, stir together filling ingredients until blended and smooth. Spread filling evenly over tops of chocolate chunk cookies. Top each with 1 peanut butter cookie, bottom side down; gently press together.