This ultra-smooth buttercream is not too sweet and is our frosting of choice when we want a silken, elegant texture and delicate flavor. It is based on meringue and a cooked sugar syrup, so it is a more complex Italian meringue buttercream recipe than a standard confectioners’ sugar-based frosting, but we think the results are well worth it. Vanilla is the basic choice, but it can also easily be turned into chocolate, espresso, raspberry, lemon and many more variations.
A stand mixer is recommended, as the meringue will have to whip for quite a while to cool down enough before the butter is added; a candy thermometer is also helpful. There is a high ratio of butter in this buttercream recipe, which means that it is very firm when chilled. Any cake frosted with Italian meringue buttercream (we call it IMBC in the kitchen) should be served at room temperature when its texture will fully blossom into a silky, creamy, luscious result.
This recipe makes a very generous amount – plenty to fill and frost a 3- or 4-layer cake plus lots of swirls and decorations on the outside. It freezes very well so any extra can be stored for up to a month.
- 1¼ cups sugar, divided into 1 cup and ¼ cup
- ⅓ cup water
- 6 large egg whites, at room temperature
- ¾ teaspoon cream of tartar
- 2¼ cups (4½ sticks) unsalted butter, very soft, cut into pieces
- Place 1 cup of sugar and water in a small saucepan. Stir to wet sugar. Bring to a boil over medium-high heat, swirling pan occasionally. Dip pastry brush in cold water and wash down sugar crystals from the sides of the pot once or twice. Allow sugar mixture to simmer gently as you proceed with egg whites.
- Meanwhile, place egg whites in a clean, grease-free mixing bowl and whip until frothy on low speed using the wire-whip attachment of a standing mixer. Add cream of tartar and turn speed to medium-high. When soft peaks form, add ¼ cup sugar gradually. Continue whipping until stiff, glossy peaks form.
- Bring the sugar/water mixture to a rapid boil and cook until it reaches 248˚ to 250˚ F. As syrup cooks, check visual cues to assess doneness if you do not have a thermometer: it starts out with a thin consistency and many small bubbles covering the entire surface. As the water evaporates, the mixture will become visibly thicker. Bubbles become larger and pop open more slowly. At this point the syrup definitely looks thickened, but it has not begun to color; this is the firm ball stage – if you drop a bit of the syrup into a glass of cold water it will form into a ball. When you squeeze the ball between your fingertips, it will feel firm and the syrup is ready.
- With the mixer running, pour syrup in a thin, steady stream directly over the meringue. Do not pour any on the whip or the sides of the bowl. Whip meringue until cool to the touch; this could take several minutes. With the mixer running, add butter a couple tablespoons at a time. Keep beating until the buttercream is completely smooth and spreadable, somewhere in texture between peanut butter and mayonnaise. Now the buttercream is ready to use. Any flavorings may be added at this point; variations are given below. Refrigerate up to 1 week in an airtight container or freeze up to 1 month. If frozen, defrost in the refrigerator overnight and bring to warm room temperature before re-beating. Always re-beat before using.
- Vanilla - Add 1 tablespoon vanilla extract towards the end of beating.
- Liqueur-Accented Buttercream – Add approximately 1/3 cup of liqueur/alcohol to every batch. Adjust taste as needed. Try Grand Marnier, Cointreau, Amaretto di Saronno, Kahlua, rum, to suggest a few.
- White, Milk or Dark Chocolate Buttercream – Note that white chocolate will make the buttercream a creamy ivory color; milk chocolate will have an almost pink-ish tinge and semi or bittersweet chocolate buttercream will be a milk chocolate color. – Add 12 ounces of melted and cooled white, milk, semi-sweet or bittersweet chocolate towards end of beating. Whip until the chocolate is thoroughly incorporated.
- Espresso Buttercream – Dissolve 2 tablespoons instant espresso powder (such as Medaglia d’Oro) in 2 tablespoons boiling water or warmed Kahlua. Add towards the end of beating, whipping thoroughly to incorporate. The coffee flavor can be adjusted up or down according to your liking.
- This recipe can read as complicated. Seeing it being made is very helpful. Check out our video.
- Temperature is crucial with this Italian meringue buttercream recipe. If the meringue is warm when butter is added, it will become soupy. If the butter is too cold, the buttercream will be lumpy and too firm. If your buttercream is too loose, place the bottom of the bowl in a larger bowl filled with ice water. Check every few minutes until its texture firms up, then whip until smooth. If the mixture is too stiff, just keep whipping, it might smooth out. Alternately, you can aim a hot hair dryer at the outside of the bowl to warm up the buttercream quickly, or place a cup of buttercream in the microwave for a few seconds until it becomes extremely soft, then add it back to the larger amount to smooth out the texture.
- If you have refrigerated or frozen the buttercream and need to bring it back to its original texture, follow the suggestions above, starting with buttercream already at a warm room temperature. If you are a daring sort you can also place the mixer bowl directly over very low heat on the stovetop, folding the buttercream over itself all the while and warming it up until it is just beginning to melt around the edges, then beat until smooth. When “reconstituting” buttercream in this way, we prefer to use the flat paddle attachment.