I always use the method from "The Cake Mix Doctor" (and use it for ANY flavor cake mix): BASIC YELLOW BUTTER CAKE 1 yellow cake mix (18-1/4 oz.) 1 stick butter (8 Tblsp.) butter, melted (do not use margarine) 1 cup milk (2% or whole  not skim) 3 large eggs 2 tsp. Vanilla extract Preheat oven to 350° F. Grease and flour two 8-inch round cake pans. In large mixing bowl, combine ingredients listed above. Beat just until blended, and no lumps remain. Pour into pans and bake at 350° F. for 27-29 minutes or until cake tests done. If making cupcakes, bake for 20 minutes.

There's no trick to it. It firms up on its own as it cools. I've had success by nuking frosting at 50% in 5 second increments until it's just barely just liquified. I test by stirring. It only needs to be warm enough to be dip-able. In my mind, (your mileage may vary) warming the frosting in a shallow, flat-bottomed container, barely bigger than your cubes, would be less messy than pouring... you could dip one side at a time, and if you worked quickly, your finger marks in the frozen cake would fall out as it cooled. I learned this trick from an awesome book I bought my niece and nephew for Christmas. They describe the technique on pages 18 & 19, which you can see by clicking on the "search inside this book" link, entering the work "microwave" in the search pane, selecting the second search result, and turning to page 19 with the right hand arrow. (For the record, the book is way fun!) I tried this dipping technique with cupcake frosting and the results were so flawless that the ladies I served them to assumed I'd done something very difficult and fancy. The punchline was that it took less time to dip (from scratch) cupcakes into warmed white Duncan Heinz frosting (with a bit of yellow food coloring and lemon extract added) than it would have taken to frost by the traditional method. The frosting firmed up a bit and they looked beautiful. This book also demonstrates a stupid-simple technique of drawing a design on a paper template, slipping the template on wax paper, melting some colored wafers, spooning them into a ziploc, cutting a tiny hole in the corner, and drawing on the wax paper. To see an example, enter the word "monarch" in the search pane and see pages 77-79. Or just buy the book. It's a fun jumping-off point for the imagination.

I think they would be easier to cut frozen. I would try it, if not defrost slightly and cut. Cakes and breads can be refrozen no problem.

Haven't you seen My Big Fat Greek Wedding? It's a buuunt cake...you stick a plant in the middle of it! Opa! How about a vanilla bean sauce with a berry (strawberry or rasberry) sauce swirled in on the plate and the cake on top. In a pinch, a good vanilla bean ice cream that has melted makes a good cake 'sauce'; puree some berries; dig in. I guess you could put a scoop of ice cream in the middle...a mint leave?