Preheat oven to 350°F (180°C).
Liberally grease two 8" round cake pans with vegetable shortening, and/or spray with baking spray.
Empty cake mix into a bowl, along with eggs and water. Beat until smooth.
Carefully add melted butter, mix on medium speed until smooth.
Divide batter among prepared cake pans.
Bake in preheated oven until knife inserted into center of batter comes out clean and cake springs back - about 25-30 minutes.
Allow to cool 10-15 minutes before turning cakes out onto baking rack to cool fully.
Ideally, allow to cool to room temperature, wrap tightly with plastic wrap. Allow cake to sit overnight, make frosting & ice cake/cupcakes the following day.