How to Make Silky Swiss Meringue Buttercream Frosting for Cakes and Fillings

This Swiss Meringue Buttercream recipe makes a smooth, fluffy, and pipeable frosting that holds its shape while tasting light and creamy. It starts with a simple Swiss meringue base of egg whites and sugar, then whips in butter for structure and flavor. Use it as a cake filling, cupcake topping, or smooth frosting layer. Unlike crusting frostings, this version gives you a clean, professional finish and a balanced sweetness that’s never overwhelming.

The method hinges on a cooked meringue base that stabilizes the egg whites before whipping. This creates a glossy foundation that holds air while staying firm enough to support butter.

Unlike American buttercream, which starts with butter and powdered sugar, this Swiss buttercream frosting begins with heat. The sugar dissolves directly into the egg whites, which eliminates grit and boosts structure.

The key measurement here is temperature. Once your egg white and sugar mix reaches 160°F, the proteins set just enough to whip into stiff peaks. Skip that mark and the texture won’t hold. Go too far past it and you’ll start scrambling the eggs. I always keep my thermometer clipped to the bowl rim for control.

Why These Ingredients Matter

Five large egg whites bring protein structure and moisture. I use fresh, not boxed, for reliable volume. Pasteurized whites don’t whip the same.

Granulated sugar helps the meringue hold its shape and brings the only sweetness this buttercream needs. I’ve tested superfine sugar, but regular granulated gives me the most stable whip.

Unsalted butter adds the creaminess and structure. I cube it while it’s still slightly cool, not fully soft, to keep the buttercream from breaking.

Vanilla extract rounds out the flavor. I always use pure, not imitation. For a softer taste, this vanilla buttercream pairs well with delicate sponge layers or fillings like Diplomat Cream.

Just a pinch of salt changes everything. It keeps the frosting from tasting flat. Skip it and you’ll notice.

Spotlight on Temperature Control

The meringue stage is where most bakers hesitate. If you don’t hit 160°F and fully dissolve the sugar, you’ll taste grit. If you stop whipping before the bowl cools, your butter will melt and break the emulsion.

I touch the outside of the metal bowl every minute or two. It should feel completely cool before you start adding butter. That’s the signal.

And yes, the curdled look midway through is expected. Every batch I’ve made has gone through that phase. Just keep mixing.

Mixing the Buttercream: Step by Step

Start with a clean metal bowl over simmering water. The egg whites and sugar should be stirred constantly until they feel smooth between your fingers. No grainy texture.

Once off the heat, transfer it to your mixer and whip until the meringue is thick, glossy, and stiff. It should form peaks that don’t fall. At this stage, it’s similar to the base for Chocolate Cake Filling but much lighter.

Now switch to the paddle attachment and add your butter slowly. One cube at a time. If it starts to look like soup or scrambled eggs, just keep going. This phase takes patience, but you’ll see it pull together.

Add vanilla and salt at the end. If you’re flavoring with melted chocolate, fold it in gently once the base is stable.

Know When It’s Done

The final buttercream should look smooth and glossy, with no streaks or lumps. It spreads easily and holds sharp ridges when piped.

If it’s too loose, chill it for 10 minutes and whip again. If it’s dense and greasy, you likely added butter before the meringue cooled. I’ve been there. it’s fixable. Let it rest, then beat it again from the start.

If you’re trying a lighter option, Whipped Cream Frosting gives a differenr result, but isn’t as stable in warm kitchens.

Flavor Variations to Try

For chocolate Swiss buttercream, melt 100g dark or milk chocolate and cool it fully before folding in.

Fruit variations need thickened puree. I usually cook down berries until they reduce by half. Add 2–3 tablespoons at a time to avoid breaking the structure.

Lemon curd can be folded in too, for a tangy twist. Start with one tablespoon and taste as you go. You can also try pairing with Vanilla Buttercream Frosting if you need contrast layers.

Storage and Reuse

Store leftover buttercream in an airtight container in the fridge for up to one week. I always bring it back to room temperature, then re-whip for five minutes before using again.

You can freeze it for up to three months. Thaw overnight in the fridge, let it sit out, and re-whip until fluffy.

If your frosting develops air pockets or feels too dense, mix it slowly with a paddle attachment for 1–2 minutes to smooth it out.

Tips from My Kitchen

Always start with a grease-free bowl. Even a tiny speck of fat can collapse your meringue.

If using salted butter, skip the added salt. The flavor balance shifts quickly.

Use a clip-on thermometer during the heating stage. Eyeballing doesn’t work here.

Don’t rush the cooling. It makes all the difference in structure. I’ve learned this the hard way more than once.

How to Use This Buttercream

Spread between cake layers as a cake filling. Pipe high swirls on cupcakes.

Frost tall layer cakes with clean, crisp edges. Use under fondant for a stable finish.

Flavor with coffee for mocha layers.

Save This Swiss Meringue Buttercream Recipe

Add this recipe to your Pinterest board so you always have it ready for your next bake.

Let me know in the comments if you’ve tried it, or if you made a variation. I’d love to hear how it worked out for you.