Prep the butter: Cut it into large pieces, about 8 per stick. Leave on counter. Should still be firm. If your kitchen is warm, put back in fridge for few mins.

Make the syrup: Combine the sugar and water in the small saucepan over a medium flame until it reaches the softball stage (238°F) remove from heat. DO NOT let it heat to 240

Meanwhile, Beat the yolks in bowl of a stand mixer fitted with the whisk attachment. Whisk on high speed until pale and thick.

With the mixer on low speed, slowly add the syrup to the yolks to avoid splattering the syrup on the beaters. Stop pouring every 10 seconds or so and increase the speed to high, then switch it to low and drizzle in more syrup. Do this until all the syrup is incorporated. Beat on high speed until the mixture has cooled to room temperature. This can take about 10 minutes.

Add the butter one cube at a time, mixing well in-between each addition.

Add vanilla. Add the vanilla (or other flavoring) and continue to beat until the buttercream is smooth and slightly stiff.