You didn't indicate whether you wanted scratch or doctored. I am a hobby baker, but have found these two recipes will produce excellent, consistent, smooth results. (I use other recipes in addition to these, but for a guaranteed success, these are my "go-to" recipes. They can also be changed with different additions to the recipes.)
INDYDEBI CRISCO-BASED BUTTERCREAM--(Excellent for hot/humid areas):
(IndyDebi is a very experienced decorator/caterer:
http://cateritsimple.blogspot.com/)
Single Batch Recipe:
1-1/3 cups Crisco (BETTER: store brand shortening with 3 grams of trans-fats, or BEST, a specialty cake supply product called high-ratio shortening. As of 2010 Crisco no longer contains trans-fats.)
1/3 to 1/2 cup milk, depending on consistency needed
3 Tbsp powdered Dream Whip (powdered whipped topping mix made by Kraft Foods)
2-3 Tbsp clear vanilla, depending on personal taste (optional: almond extract, or lemon extract )
2 lbs. powdered pure cane sugar
IndyDebi says: There's no wrong way to mix this. I usually mix all but the powdered sugar & milk for a minute or two, then gradually alternate the sugar & milk, but the only reason I do this is to avoid the "sugar-splash" factor. The longer the mixer runs, the smoother it gets. Sifting the powdered sugar before blending helps with smoothness but is not necessary.
NOTE: Based on recommendations from other users of her recipe: 1) I make a double batch so the beaters are totally immersed to avoid air bubbles, 2) I beat the shortening, milk, Dream Whip, and vanilla for 10-15 minutes BEFORE I add the powdered sugar. I refrigerate or freeze leftover icing.
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This cake recipe is very dependable, consistent, tasty, & durable enough to stack and carve. It also makes lovely cupcakes. You can use gel colors to color the batter. This is a version of a cake recipe from the book: The Cake Mix Doctor, by Anne Byrn, ISBN: 0761117199. [EVERY baker should own this book!]
Sour Cream White Cake
1 package (18.25 oz.) Duncan Hines white cake mix
1 cup sour cream
1/2 cup canola oil
3 large eggs
1 teaspoon pure almond (you can also used vanilla, lemon, etc.) extract