Directions

1. 1

   Cut the vanilla bean lengthwise and use the tip of a knife to scrape out the tiny seeds into a small bowl. Place the empty vanilla pod in a medium heavy-bottomed saucepan. Pour in the whole milk and heavy cream, then place the pan over medium-low heat. Warm gently until the mixture just begins to steam and show small bubbles around the edges. Remove from heat, cover the pan, and let steep for 10 minutes.

2. 2

   In a stand mixer fitted with the paddle attachment, combine the room-temperature egg yolks on low speed until blended. Gradually sprinkle in the sugar while mixing on low, then add the salt and scraped vanilla bean seeds. Increase the mixer speed to medium-high and beat for approximately 5 minutes until the mixture is very pale, thick, and forms a ribbon when the paddle is lifted. Stop and scrape the bowl, then reduce speed to low and gently beat in the cornstarch until no lumps remain.

3. 3

   Carefully strain the warm milk mixture into a measuring cup, discarding the vanilla pod. With the mixer running on low speed, pour the hot liquid into the egg-sugar mixture very slowly, beating constantly to prevent curdling. Once fully combined, scrape this tempered custard into the saucepan and place over medium-low heat. Stir constantly with a wooden spoon for 5–7 minutes as the mixture thickens and just begins to bubble gently at the edges. Switch to a whisk and whisk vigorously for 3–4 minutes until the custard becomes glossy and completely smooth. Remove from heat and pass through a fine-mesh sieve into a clean bowl. Whisk in the vanilla extract and 1 tablespoon of butter until fully incorporated.

4. 4

   Press a sheet of plastic wrap directly onto the surface of the warm custard to prevent a skin from forming. Refrigerate for at least 1 hour, or until completely chilled.

5. 5

   Transfer the chilled custard to a stand mixer fitted with the paddle attachment. Add the 1 cup of room-temperature unsalted butter in 3–4 pieces. Beat on medium-high speed, stopping occasionally to scrape the bowl, until the mixture is light, fluffy, and the butter is fully incorporated. The finished buttercream should be pale and airy. Use immediately or store in an airtight container in the refrigerator.