1Heat oven to 350°F (325°F for dark or nonstick pans). Place paper baking cup in each of 24 regular-size muffin cups. In large bowl, beat cupcake ingredients with electric mixer on low speed 30 seconds, then on medium speed 2 minutes. Divide batter evenly among muffin cups. Bake 18 to 23 minutes or until toothpick inserted in center comes out clean. Cool in pans 10 minutes; remove from pans to cooling rack. Cool completely, about 30 minutes.
2In 2-quart saucepan, melt butter over medium heat. Stir in brown sugar; heat to boiling, stirring constantly. Stir in milk; return to a boil. Remove from heat. Beat in powdered sugar with electric mixer on low speed until smooth. Frost cupcakes. (If frosting becomes thick, stir in 1/2 teaspoon milk.)
3For each cupcake, pipe computer keyboard and screen onto 2 chocolate candy bars. Pipe frosting on 1 long edge of keyboard; place screen onto keyboard. Pipe small amount of frosting on bottom of computer; place on cupcake. Store loosely covered.