Swiss meringue buttercream takes its name from the Swiss method of warming egg whites and sugar before whipping them into a meringue, while this mock version is a quick home-baking shortcut. Marshmallow creme and butter make a smooth, rich frosting without a stovetop or raw egg whites, and the result is easy to spread or pipe onto cakes and cupcakes.
Ingredients
- 1 cup (227 g) unsalted butter, softened but not melted
- 1 jar (7 ounces / 198 g) marshmallow creme or marshmallow fluff
- ¾ cup (90 g) powdered sugar, sifted if lumpy
- 1 teaspoon (5 ml) pure vanilla extract
- ⅛ teaspoon (about 0.75 g) fine salt
Instructions
- Check the butter. It should give slightly when pressed but still feel cool and hold its shape. If it is greasy, shiny, or partly melted, chill it briefly before starting; melted butter will make the frosting loose rather than fluffy. Have the marshmallow creme at room temperature so it blends readily.
- Beat the butter. Put the softened butter in a large mixing bowl. With a hand mixer or stand mixer fitted with the paddle attachment, beat on medium speed for 3 to 4 minutes, scraping the bowl once or twice. The butter should look paler and creamy, with no firm lumps clinging to the sides.
- Add the marshmallow creme gradually. Add it in three portions, beating on medium-low after each addition until incorporated. Scrape the bottom and sides of the bowl, then beat for about 1 minute more. Gradual additions help the butter and creme combine into an even base instead of leaving sticky streaks.
- Mix in the sugar and flavorings. Add the powdered sugar, vanilla, and salt. Start on low speed so the sugar stays in the bowl, then increase to medium and beat for 1 to 2 minutes. Stop once the frosting is uniform; prolonged high-speed beating can add unnecessary air and make piping less tidy.
- Check the texture. The frosting should be soft enough to spread but firm enough to hold a simple piped swirl. If it feels too soft, chill the bowl for 10 minutes and beat briefly again. If it is stiff, let it stand at room temperature for a few minutes and mix on low. Avoid adding liquid unless absolutely needed, because even a small splash can loosen the frosting.
- Use it right away. Spread the frosting over fully cooled cake or cupcakes, or transfer it to a piping bag. This quantity is enough for about 12 cupcakes with a moderate swirl, or a thin-to-medium coating on a small single-layer cake. For a tall layer cake or very generous piping, make a double batch.
Tips
- Start with the right butter temperature. Softened butter is pliable, not oily. If your kitchen is warm, cut the butter into pieces and check it often rather than leaving it out until it turns glossy. Butter that is too cold can leave small lumps; butter that is too warm may produce a slack frosting that needs chilling.
- Sift only when necessary. Powdered sugar can clump in a humid pantry. Sifting makes it easier to blend and reduces the chance of tiny dry pockets, but freshly opened, loose sugar can go straight into the bowl. Add it on low speed to avoid a cloud of sugar dust.
- Choose the right substitute carefully. Marshmallow creme is the defining shortcut here; regular marshmallows are not a direct one-for-one replacement because they contain a different amount of moisture and are harder to blend evenly. If you cannot find creme, use a recipe specifically written for melted marshmallows rather than guessing at a swap. The frosting’s sweetness and texture will change.
- Adjust flavor in small increments. The base is sweet, so taste before adding more sugar. A little extra vanilla is easy to incorporate, while liquid flavorings can soften the frosting. For a stronger flavor, use a small amount of concentrated extract or finely grated citrus zest instead of pouring in juice.
Serving Suggestions
Use this frosting on vanilla, chocolate, or red velvet cupcakes, where its soft marshmallow flavor complements familiar cake flavors without overpowering them. It also works on a cooled sheet cake, sandwich cookies, brownies, or a simple two-layer celebration cake. For neat cake slices, chill a frosted cake until the buttercream is set, then let it sit briefly at room temperature before cutting so the frosting is not hard.
For a simple finish, spread it with an offset spatula and make loose swirls with the back of a spoon. To pipe, use a large open-star or round tip and keep the bag at a comfortable room temperature; very warm hands can soften the butter in the bag. Pair the frosting with fresh berries or sliced fruit when serving, but add juicy toppings close to serving time so their moisture does not soften the surface. This recipe is a sweet buttercream, not a light, toasted meringue topping, so it is best used as a frosting or filling rather than spooned onto a hot dessert.
Variations
Chocolate: Beat in ¼ cup (21 g) unsweetened cocoa powder with the powdered sugar. Sift the cocoa first, since it commonly forms lumps. This adds a mild chocolate flavor; for a deeper result, use Dutch-process cocoa, keeping in mind that the frosting will taste less bright and more rounded.
Citrus: Add 1 teaspoon (about 2 g) finely grated lemon or orange zest with the vanilla. Zest brings a fragrant citrus note without adding much liquid. A small amount of citrus extract can also work, but add it gradually because extracts vary in strength.
Almond or other extracts: Replace up to ½ teaspoon (2.5 ml) of the vanilla with almond extract, or use another baking extract that suits your cake. Do not swap the entire teaspoon without tasting; some extracts are much more intense than vanilla and can quickly dominate the marshmallow flavor.
Less sweet-tasting finish: Keep the recipe quantities the same and add a tiny extra pinch of salt, tasting as you go. Salt balances sweetness but does not remove sugar. You can also pair the frosting with a tart fruit filling or a less-sweet cake. Reducing the powdered sugar substantially may make the frosting softer, so avoid cutting it out completely if you need defined piping.
Color: Use gel food coloring a little at a time. Gel adds less liquid than many liquid colors, helping the frosting keep its consistency. Beat in a small dab, scrape the bowl, and wait a minute for the color to even out before adding more; the shade may deepen slightly as it sits.
Storage and Reheating
Because this frosting contains butter, keep it covered and refrigerate it within 2 hours of preparation or serving. In an airtight container, it keeps for up to 4 days in the refrigerator. A cake or cupcakes topped with it should also be covered and refrigerated within 2 hours; follow the storage needs of any more perishable filling or topping on the dessert.
To use refrigerated frosting, let it stand at room temperature until it is pliable, usually 30 to 60 minutes depending on the amount and room temperature. Beat it briefly on low or medium-low until smooth. It may look separated or firm straight from the fridge, but gentle warming and mixing usually bring it back together. Do not microwave the whole batch: the edges can melt before the center softens, leaving an oily texture.
For longer storage, freeze the frosting in an airtight, freezer-safe container for up to 2 months for best quality. Thaw it overnight in the refrigerator, then bring it toward room temperature and beat briefly before using. Do not leave the frosting or a frosted cake out for extended periods; return leftovers to the refrigerator promptly.
Frequently Asked Questions
Is mock Swiss meringue frosting the same as Swiss meringue buttercream?
No. Traditional Swiss meringue buttercream starts with egg whites and sugar warmed together and whipped into meringue before butter is added. This mock version uses marshmallow creme as a shortcut, so it is quicker and does not require heating or whipping egg whites. It has a related smooth, buttery character, but it is sweeter and does not have exactly the same texture or flavor.
Can I make this frosting without a stand mixer?
Yes. A handheld electric mixer works well; use a deep bowl and scrape it often. Mixing by hand with a sturdy whisk is possible, but creaming the butter thoroughly and blending the sticky marshmallow creme takes considerable effort. A stand mixer is convenient, not essential. Avoid using a food processor, which can warm the butter and make it difficult to judge the texture.
Why is my frosting runny?
The most common cause is butter that was too warm or partly melted, especially in a hot room. Refrigerate the bowl for about 10 minutes, then beat briefly and check again. If it is still loose, chill it a little longer rather than immediately adding a large amount of sugar, which can make the result overly sweet. Also check that the cake was completely cool before frosting it.
Can I use salted butter?
Yes. Use the same 1 cup (227 g) amount of softened salted butter and leave out the added fine salt at first. Taste the finished frosting, then add a small pinch only if it needs balancing. Salt levels differ among butter brands, so starting without extra salt gives you more control.
Can I pipe flowers or detailed decorations with it?
It can pipe borders, rosettes, and straightforward swirls when it is cool but still pliable. It is softer than many stiff American buttercreams, so very fine petals or decorations that must hold up in a warm room may lose definition. Chill the frosting briefly if it softens in the piping bag, and keep finished decorations cool until serving.
Can I make it ahead?
Yes. Make it up to 4 days ahead and refrigerate it in an airtight container, or freeze it for up to 2 months. Before using, thaw frozen frosting in the refrigerator, let chilled frosting soften until pliable, and beat it briefly until smooth. If you are making a decorated cake ahead, refrigerate it covered and allow a little time for the frosting to soften before serving.
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