Italian Buttercream

Set up your workspace. Fit a candy thermometer on a medium saucepan, making sure the tip is in the syrup but not touching the bottom of the pan. Add sugar and water and stir just to moisten. Place your mixer bowl with egg whites on the stand mixer and attach the whisk. (This recipe moves quickly once the syrup is ready.)

Clean bowl reminder. Egg whites hate grease. Make sure your bowl and whisk are clean and dry, with no buttery film. If you’re not sure, wipe them with a little vinegar or lemon juice, then dry well.

Start the syrup. Bring the sugar and water to a boil over medium-high heat. Once it boils, do not stir. Let it cook until it reaches 245 to 250°F (118 to 121°C), with 248°F (120°C) as the sweet spot.

Pip’s note: If you see sugar crystals on the sides of the pan early on, you can gently brush them down with a water-damp pastry brush. After it is boiling steadily, leave it alone.

Whip the egg whites. When the syrup hits about 230°F (110°C), start whipping the egg whites on medium speed until foamy, then add the salt. Increase to medium-high and whip to soft peaks.

If your whites reach soft peaks before the syrup is ready, just turn the mixer down to low to hold them for a minute or two. You want soft, glossy peaks right as the syrup comes to temperature, not dry or stiff whites.

Stream in the hot syrup. With the mixer running on medium-high, carefully pour the 245 to 250°F syrup in a slow, steady stream down the side of the bowl, aiming between the bowl and the whisk. Avoid pouring directly onto the whisk, which can fling syrup.

Whip until cool and glossy. Keep whipping on medium-high until the meringue is thick, glossy, and the bowl feels neutral, not warm. This usually takes 8 to 12 minutes.

Add butter gradually. Switch to the paddle attachment if you have one (optional, but it helps make the buttercream extra smooth). With the mixer on medium speed, add butter 1 tablespoon at a time, letting each piece blend in before adding the next.

Halfway through, it may look curdled, grainy, or slumpy. Keep going. Once all the butter is in, increase speed to medium-high and beat until it becomes silky and smooth, about 3 to 5 minutes.

Flavor it. Mix in vanilla (and any optional flavor additions) on low speed. Scrape the bowl, then mix again briefly until even.

Use right away or prep for piping. For smooth frosting, use immediately. For piping details, you can chill the buttercream for 10 minutes, then stir it with a spatula to knock out air bubbles and load your piping bag.

How to smooth it on a cake. Apply a thin crumb coat first, chill the cake 20 minutes, then add the final layer. A warm metal bench scraper or offset spatula helps: dip in warm water, wipe dry, then smooth.