Classic American Vanilla Buttercream

• Prep20 min
• Cook0 min
• Total20 min
• Serves24

Ingredients

Powdered sugar

• 600 g granulated sugar (3 cups)
• 16 g cornstarch (2 tbsp)

Buttercream

• 340 g unsalted butter (1 1/2 cups, 3 sticks), softened but cool, in pieces
• 2 tsp vanilla extract (clear vanilla for a whiter frosting)
• 1 pinch salt
• 45 g heavy cream or whole milk (3 tbsp), plus more if needed

Instructions

1. Take the butter out of the fridge 30 to 60 minutes ahead. It is ready when a finger dents it easily but it still feels cool and does not look shiny, about 18-20°C (65-68°F). Cold butter leaves little lumps, and butter that is too soft makes a greasy frosting that will not hold a swirl.
2. Make the powdered sugar: place half of the granulated sugar (300 g) and 1 tbsp cornstarch in the clean, completely dry mixing bowl, with no butterfly whisk, and mill 15 sec/speed 10. Wait 1 minute for the sugar dust to settle before opening the lid, transfer to a bowl and repeat with the rest. A drop of water makes sugar clump, and the cornstarch keeps it powdery, like store-bought. If you use 600 g (5 cups) store-bought powdered sugar, skip this step.
3. Insert the butterfly whisk, add the butter and whip 3 min/speed 4, scraping down the sides halfway, until it is pale, almost white, and creamy. This first whipping beats air into the butter before the sugar makes it heavy.
4. Add a third of the powdered sugar and mix 30 sec/speed 3 with the measuring cup in place. Scrape down the sides and repeat twice with the rest. Adding the sugar in parts keeps it from puffing out of the bowl and leaving dry pockets.
5. Add the vanilla, salt and cream and whip 3 min/speed 4, until light and fluffy. The salt does not make it taste salty: it softens the sweetness and makes the vanilla stand out.
6. Check the texture with the spatula. For piping, it should hold a peak that bends only at the very tip; for spreading, it can be a little softer. To soften it, add 1 tsp cream at a time and whip 10 sec/speed 3.5. To firm it up, refrigerate it 10 to 15 minutes and whip 10 sec/speed 3.5.
7. For a smooth cake, stir the buttercream by hand with the spatula for 1 minute to push out the big air bubbles. For cupcakes, spoon it into a piping bag with a large open star tip and pipe a swirl on each completely cool cupcake (warm cake melts the butter), starting at the outer edge and spiraling up toward the center.

Tips

• For a whiter buttercream, whip the butter the full 3 minutes (or even 5), use clear vanilla and add a tiny dot of violet gel color on the tip of a toothpick: violet cancels the yellow of the butter, so the frosting looks white, not purple.
• Florida heat: butter softens fast in a warm room, and at an outdoor party the swirls can slump. For a stiffer frosting that holds up better, replace 115 g (1/2 cup) of the butter with cold vegetable shortening, which melts at a higher temperature, and keep the cupcakes in air conditioning until serving. Frosted cupcakes keep 2 days in an airtight container in a cool room, or 4 days in the fridge.
• Chocolate buttercream: add 55 g (2/3 cup) unsweetened cocoa powder to the second batch of sugar before milling, so the TM7 breaks up every cocoa lump, and use 60 g (4 tbsp) cream instead of 45 g. For a deeper flavor, dissolve 1 tsp instant espresso powder in the cream.
• To color it, use gel colors, not liquid ones (liquid thins the frosting): add them in step 5, a little at a time, and remember the color deepens as it sits for an hour. For flavor, swap 1 tsp of the vanilla for almond, lemon or coconut extract, or mill the zest strips of 1 lemon or orange with the first batch of sugar. For a pink strawberry buttercream, mill 15 g (3/4 cup) freeze-dried strawberries with the sugar.