Mousseline Buttercream Frosting

Using only egg whites gives this frosting a lovely white hue, but it’s also easy to color with food colorings. It’s soft enough to pipe borders and stiff enough to pipe flowers and other embellishments. Customize it with flavoring extracts or flavored liqueurs and spirits such as bourbon, vodka or rum.*

Prep: 30 min
Yield: 4 cups
Ingredients
    • 1 cup sugar
    • 1/4 cup (2 fluid ounces) water
    • 5 large (5 fluid ounces) egg whites, room temperature
    • 1/2 teaspoon cream of tartar
    • 4 sticks (2 cups) unsalted butter, room temperature

Optional additions:

  • Vanilla or other flavored extract, to taste
  • 3 fluid ounces bourbon* (or any spirits or flavored liqueur)
  • Food coloring
Directions
  1. BRING sugar and water to a boil in heavy-bottomed saucepan and heat until it reaches soft-ball stage (265℉).
  2. WHISK egg whites and cream of tartar together in the bowl of an electric mixer fitted with a whisk attachment. Whisk until firm peaks form.
  3. REMOVE hot sugar from stove and pour into a heat-resistant measuring cup. With the mixer on, slowly pour hot sugar into egg whites mixture, avoiding hitting the whisk. Keep whisking on high until egg whites are completely cooled.
  4. ADD butter a little at a time, waiting for each addition to be incorporated before adding more, until all butter is incorporated. Add flavoring or food coloring if using (optional).
  5. KITCHEN TIPS:

    1.*Frostings with bourbon or other alcohol-based spirits added are not suitable for children, as the alcohol in them remains full strength and does not evaporate or “cook out.”

    2. Butter should be room temperature but not too soft; it should hold a finger imprint when touched. Take butter out of fridge 20 minutes before starting recipe, cut it in cubes and let it sit out until ready to use.

    3. Make sure meringue is completely cool after adding hot sugar to it, before adding butter. If it is still warm, it will melt the butter.

    4. If frosting looks like it has separated (usually toward the end) don’t worry, this is normal. Just keep the mixer on high and it will come together and smooth out.

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  • To be honest, this recipe is actually an Italian Buttercream. The ingredients and technique is totally Italian Buttercream A TRUE mousseline buttercream, also known as a German buttercream,also known as Creme Mousseline, is simply 2 parts pastry cream to1 part soft butter. Both should be room temperature before combining and whipping, and THEN you have a mousseline cream.

    • Hi Chef Sheila, We LOVE hearing from Pasty Chef's that follow Swans Down Cake Flour. Thank you for the insight. We will certainly pass your comments on to The Kitchen, and will make adjustments if necessary. Happy Baking!

    • Hi Blimey, This frosting should be refrigerated, especially if you live in a warmer climate. BUT you should take it out of the fridge and let stand before serving so the frosting is close to room temperature. Happy Baking!

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