Heat oven to 350°F. Line 24 muffin cups with paper baking cups. Prepare cupcakes as directed on box using water, oil and eggs. Fill muffin cups 2/3 full.
Bake 21 to 26 minutes or until cupcakes spring back when touched lightly in center. Remove from pans. Cool completely, about 30 minutes.
Reserve 8 cupcakes. (Wrap and freeze remaining cupcakes for later use.)
On cookie sheet, decorate each ice cream scoop to resemble a mouse, using 2 cookies for ears, and small candies and pretzels for facial features and whiskers. Cover loosely with plastic wrap and freeze. When ready to serve, place cupcakes on 8 dessert plates. Top each cupcake with decorated ice cream.