Let’s create this exquisite Chocolate Coffee French Buttercream step-by-step:

1. Whip the Egg Yolks:

Place the egg yolks into the clean bowl of your stand mixer fitted with the whisk attachment.

Whisk on medium-high speed for a few minutes until the yolks are thick, pale yellow, and have increased in volume. Leave the mixer ready.

2. Cook the Sugar Syrup:

Meanwhile, combine the water and granulated sugar in a small, heavy-bottomed saucepan. Stir briefly just to moisten the sugar.

Place the saucepan over medium-high heat. Attach a candy thermometer to the side, ensuring the bulb is submerged but not touching the bottom.

Bring the syrup to a boil without stirring. Wash down any sugar crystals from the sides of the pan using a pastry brush dipped in water.

Continue boiling until the syrup reaches exactly 238°F (115°C) on the candy thermometer (soft-ball stage). This will take about 5 minutes – watch carefully!

3. Add Syrup to Yolks (Temper & Cook):

Immediately remove the syrup from the heat once it reaches temperature.

Turn the stand mixer (with the whipping yolks) to medium speed.

Very carefully and slowly, pour the hot sugar syrup in a thin, steady stream down the side of the mixing bowl into the whipping egg yolks. Avoid pouring directly onto the moving whisk, as this can cause sugar splatter or strands.

4. Whip Until Cool:

Once all the sugar syrup has been added, turn the mixer speed up to high.

Continue whisking the yolk mixture for 5 to 7 minutes, until it is very thick, pale in color, and the bottom of the mixing bowl feels just lukewarm or cool to the touch. This cooling step is crucial before adding butter.

5. Add the Butter Gradually:

Switch the mixer attachment from the whisk to the paddle attachment.

Ensure the butter is softened but still cool (around 68°F/20°C).

With the mixer running on medium-low speed, begin adding the butter, just 1 to 2 tablespoons at a time.

Allow the butter to mix in for about 15 to 20 seconds after each addition before adding the next. Scrape down the sides and bottom of the mixing bowl often.

6. Beat Through the “Broken” Stage:

As you add the butter, the mixture will likely look separated, curdled, or “broken.” Don’t panic! This is normal. Just keep the mixer running on medium speed.

As more butter is added, the frosting will start to thicken and emulsify. It will magically come together into a smooth buttercream!

7. Add Flavorings:

Once all the butter is added and the buttercream is smooth, add the melted and cooled semi-sweet chocolate, the salt, and the coffee extract (or emulsion).

Mix again on medium speed for a few minutes until the flavorings are fully incorporated and a uniform, fluffy frosting forms.

Use immediately, or store airtight.