Step 1

Using an electric hand mixer, whisk yolks and sugar until the mixture is pale and sugar is mostly dissolved. Stir in the milk. (TIP: It's best to use a bowl with high sides, so it doesn't spray out everywhere.)

Step 2

Transfer the egg yolk mixture into a small saucepan and heat over low heat, stirring frequently. Continue to cook until it’s thick like a pudding, about 5 minutes. Pour the mixture into a clean bowl and bring it to room temperature.

Step 3

Stir in butter in three batches, mixing well after each addition. I use a silicone spatula for this step.

Step 4

Add vanilla extract and continue to mix until smooth. For filling macarons, I prefer this consistency of the buttercream.

Step 5

However, if you'd like, you can also whip it until fluffy with an electric mixer. Whipped buttercream is ideal for filling cakes and cupcakes.