How To Frost A Cake With Smooth Buttercream

One of the most frequent questions I get as a cake decorator is how I get my buttercream cakes so smooth and sharp. To answer you, I’m going to be completely candid here and not pretend that my cakes are absolutely flawless every time. The truth is, with most of the cakes I design, there are plenty of opportunities to hide small flaws in the buttercream finish. A ganache drip over this crease, sprinkles around that bottom edge, and before you know it the cake appears flawless with all those problem areas covered up! Ok, maybe that’s just me being lazy creative. Despite that, I have developed some skills and learned some tips over the years that help me get pretty darn close to a flawless buttercream finish, and I’m excited to share them all with you!

I’m a visual person, having learned everything I know about cakes on YouTube. So if you’re like me, here’s a handy video tutorial on how I get those edges sharp and those sides smooth as can be. Read on after the video for my best tips to getting the look:  

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You Will Need

• Cake layers and filling
• Thin consistency buttercream like this one
• Piping bag(s)
• Cake turntable
• Metal bench scraper
• Metal angled spatula
• Hot water and towel

Step 1: Gather The Right Tools

The right tools make all the difference when you’re trying to achieve a smooth finish. You’ll notice that I’ve specified metal spatulas and scrapers in the list above. These materials allow you to heat up the tools when you’re smoothing, and just like ironing a shirt, a little heat will help smooth over any wrinkles and blemishes in the cake finish. I have used this 6-inch stainless steel bench scraper and Wilton’s 13-inch angled spatula since the beginning, and they’ve helped tremendously.

A good cake turntable is a must, and I have two of them that I love. The cheapest of the two is this one by Wilton, pictured above. It has a nice rubber circle built in to the top to prevent your cake from sliding around. I also have this Ateco turntable that comes with a rubber pad to prevent from slippage. The Ateco turntable is not only functional, it’s really pretty, and I use it to photograph my cakes on all the time.   

Step 2: Perfection Starts Inside The Cake

As they say, it’s what’s on the inside that counts. If you want a perfectly level cake, you’ve got to start with perfectly level layers. This means torting cakes that have a little too much rise in the center. My favorite tool for this is Wilton’s Cake Leveler. You can adjust the height of the leveler and slice off any extra cake in seconds, creating perfectly even layers for stacking.

As you’re filling your cakes, make sure the height of the filling is level as well. It helps to get down to eye level and make sure it’s not slanted in any way.

If you’ve got extra time on your hands, you can let the cakes settle at room temperature after you stack them, so gravity will do it’s thing before you start frosting. I almost never let my cakes settle because I keep them so cold all the time, plus I am a bit impatient, but I know this is a step that a lot of cake makers swear by.

Step 3: Mix Up The Right Buttercream Consistency

When you’re frosting a cake, you want the buttercream to be thin consistency, meaning that it’s easy to spread and holds its shape without being runny. This vanilla buttercream recipe is foolproof for this, but whatever recipe you use, test it before adding it onto the cake. A good way to test is dip a rubber spatula into the frosting. It should form peaks that aren’t too stiff, and easily spread when you move your finger over it.

If your frosting is too thick, it’ll be hard to get the sides smooth and will feel like you’re basically ripping through it. The end result can often look airbubbly and have a finish that looks like stucco. No bueno. To fix it, all you have to do is add more liquid (in most cases heavy whipping cream or whole milk) to thin it out to the perfect consistency.

Step 4: Stir The Buttercream To Reduce Air Bubbles

Air bubbles happen all the time. It usually starts with over-mixing the buttercream as the whisk or paddle attachment ends up whipping too much air into it. Sometimes it’s just a fact of life, and I still struggle with airbubbly buttercream at times, even when I’m sure not to over-mix.

In my experience with buttercream, one super helpful trick to greatly reducing air bubbles is this: before you add any buttercream to the cake, give it several stirs with your rubber spatula and press it against the sides of your mixing bowl. This will force out any unwanted air that might be trapped inside the buttercream due to your mixer. You’ll visibly see it becoming smoother and air pocket free as you stir it up.

Step 5: Apply A Crumb Coat

I know some bakers don’t believe all cakes need a crumb coat, but I do. This way, all of the crumbs end up in the first frosting layer (hence the term crumb coat) and never in the final layer. It’s just prettier that way.

To add a crumb coat, spread a thin layer over the entire cake with an offset spatula, filling in all the cracks and holes (like in between layers), and smooth it all with your bench scraper. When you’re done, it should look like a semi-naked cake that’s pretty close to level on all sides and the top. Stick it in the fridge for at least 20 minutes (even overnight is a good idea!) to let it firm up a bit before adding your final layer. Starting the final layer with a sturdy foundation is a huge help when it comes to getting a smooth buttercream finish.

Step 6: Apply The Final Layer

After your crumb coat has set, you’re ready to make that perfect buttercream cake become a reality. I’ve learned that piping the buttercream around the cake instead of applying buttercream with a spatula is a huge game changer for me. It helps to keep the buttercream even over the entire cake and makes it way easier to smooth out.

Starting at the bottom of the cake and working your way to the top, pipe the buttercream in even lines as you rotate the turntable. When you reach the top, pipe a ring around the top edge and then fill in the center of the top with buttercream.

First, smooth the top of the cake so that it’s perfectly level and smooth. 

Next, use your bench scraper to smooth the sides, scraping the excess buttercream off of the scraper each and every time. Make sure that as you scrape, the scraper is vertically level, but also about a 45 degree angle toward the side of the cake (tighter angles help reduce those unsightly lines in the cake finish). Feel free to be slow and intentional with this process.

If you notice any gaps in your cake finish, simply fill them in with buttercream and keep scraping.

As you smooth the sides of your cake, the buttercream on the sides will begin to reach higher than the top of the cake like a crown. This is what you want. To get a clean, sharp edge, take your angled spatula and level off the top, smoothing the outsides of the buttercream crown toward the center of your cake. Remember to continue scraping off the excess buttercream and cleaning your tools before smoothing the cake.

Don’t be afraid to get down to eye level and make sure your top is level. Need to raise up one side of the top? Add more buttercream and smooth it down till all is level.

Step 7: Apply A Little Heat

Even if you still have some little flaws in your buttercream finish, here is the magical tip that I’ve discovered that will literally erase them: a hot spatula. Remember how I talked about needing a metal bench scraper and angled spatula? This is why.

Run your metal scraper or offset spatula under super hot water and wipe it clean with a towel so that it’s dry but warm to the touch. Slowly smooth the sides and/or top with this heated device and you will be amazed at how smooth the buttercream becomes. Repeat heating your tools, drying them off, and smoothing the cake until you’ve got the smoothest buttercream you’ve ever seen.

Step 8: Extra Magic

If you’re finding that you’ve been at this process of smoothing for awhile and your cake is still looking a bit flawed, there’s another trick I’ve learned. Stop what you’re doing and put the cake in the refrigerator for at least an hour. The finish will harden and be much easier to work with after you’ve waited awhile.

When the buttercream is good and chilled, pick up where you left off. Apply a very thin layer of new buttercream to the entire cake and smooth it out. You will be amazed at how easy it is to smooth the buttercream when you’ve got a really firm foundation underneath to work with. This part does take a bit more time, and I don’t always do it unless I’m desperate for a smooth finish and the final design depends on it. But when I do, it’s smooth city.

Smooth buttercream cakes don’t have to be intimidating. With enough practice and finding the techniques that work for you, you’ll be a pro at this in no time. If you found the video tutorial portion of this helpful, be sure to check out my other YouTube videos! I’m adding new ones all the time, so subscribe to keep up with them.