French Buttercream

Whisk 1 whole egg plus 5 egg yolks with 340g sugar over a double boiler until the mixture reaches 71°C, stirring constantly.

Remove from heat and whisk the warm egg-sugar mixture for 5 minutes until pale, thick, and cooled to room temperature.

Cut 6g cold butter into small cubes and add gradually to the cooled egg mixture, whisking continuously until fully incorporated.