It’s not quite a piece of cake.
Credit: Photo by Dorling Kindersley: Charlotte Tolhurst via Getty Images

I’m not much of a baker. I’ve mastered a few simple quick breads, like banana bread, blueberry muffins, and zucchini bread, but I typically avoid more complicated recipes. SO, when I recently came across this stunning Tahini-Blueberry Sheet Cake with Strawberry Buttercream, I decided to branch out and go for it. After all, it seemed like a fairly simple cake recipe. The cake was as basic as the quick breads I adore, so I just had to conjure up enough confidence to make the buttercream and frost the cake.

When I was done, the cake tasted delicious. Unfortunately, little bits of cake were left crumbled throughout the frosting, blobs of strawberries doused in buttercream were tossed all over the plate, and patches of unfrosted cake poked through layers of chunky butter. When I brought the cake into work, I was so embarrassed that I blamed the disaster on transporting the cake (I should have read how to transport a cake if you don’t have a carrier).

The truth is—I made some pretty offensive, rookie frosting mistakes that made it near impossible to get that perfect, velvety-smooth swirl of buttercream. I chatted with a few folks in our test kitchen to determine the most common mistakes beginners make when frosting a cake, and how to avoid them. Fingers crossed I’ll do better next time.

Don’t Make the Frosting in Advance

It doesn’t matter which style of frosting you plan to make—as long as you make it right before you’re ready to frost. Frosting is made from majority butter and sugar, so leaving it for a long period of time at room temperature will make it too soft and refrigerating it will make the butter seize. If you’re looking to work ahead, always make your cake in advance over the frosting. You can refrigerate it overnight or freeze on a cookie sheet and individually wrap layers in plastic wrap and foil.

Don’t Frost a Warm Cake

We get it—you’re excited to eat the cake. But patience is key to avoiding a layer of runny, unflattering frosting. Baking pros in our test kitchen emphasize that it is essential to let the cake completely cool before frosting. Better yet, you can let the cake sit in the refrigerator for a while to make the process even easier.

Don’t Overbeat the Frosting

Letting your mixer go crazy for too long will bring way too much air into the butter. A proper buttercream should be pale white when the butter and sugar are incorporated. You’ll want to gradually add sugar to the bowl, adding more just as you see the previous sugar addition disappear into the butter, and then finish once it’s all mixed together. Overbeating will lead to a grainy, unappealing product.

Don’t Soften Butter to Room Temperature

Softened butter should be soft enough to hold a thumbprint when you touch it, but not soft enough to push all the way through. If the butter is too soft, it becomes far too easy to overwork. Our test kitchen bakers recommend taking the butter out to warm about 20 to 30 minutes before you’re ready to use it. Plus, frosting should never be soupy or curdled. This occasionally happens when the temperature is off and means that the frosting broke. You’ll need to refrigerate and try rewhipping.

Don’t Forget The Crumb Coat

You may think only professional bakery cakes warrant a crumb coat, but most any layered cake can benefit from it. Simply frost a thin layer over the entire cake, then chill for a bit so that the thin layer of icing can solidify—sealing in any loose crumbs and creating a cool, smooth surface for the next coat. This keeps your top layer of frosting neat and tidy.

Don’t Use Just Any Spatula

Our bakers’ utensil of choice when it comes to frosting is an offset spatula. It’s much easier to maneuver than a butter knife or rubber spatula. The trick is to avoid direct contact between the spatula and the cake itself, so little bits of cake don’t end up mixed into the frosting.

Don’t Use Powdered Sugar Directly From the Bag

It’s tempting to measure out a cup-full of powdered sugar straight from the bag to add to your butter mixture. However, you should always sift your powdered sugar first to help incorporate extra air, which helps the frosting to become light and fluffy, as well as to avoid clumps within the frosting.

Don’t Assume the Cake is Flat

Layered cakes need to be as flat as can be to avoid gaps or uneven tops. Get eye-level with the layer and slice off any bits that are uneven before frosting. Repeat this leveling off process once you frost a layer to ensure the frosting won’t lead to a lopsided cake.

Don’t Try to Make the Frosting By Hand

It may seem like the most obvious mistake, but if a recipe calls for a mixer you really need a mixer. Don’t try to hand-whip your frosting with a whisk. Invest in a good stand mixer or hand mixer for the best quality frosting.

Don’t Add Fresh Fruit Right Away

In some recipes, like the one I tried, you’ll need to include additional liquid-heavy ingredients into your frosting. I made the mistake of adding the strawberries too far in advance, and they made the frosting extra watery. For best results, be sure your fruit is dry, coat the fruit pieces with powdered sugar before adding to the frosting, and then gently fold them in.