Boil sugar and water at 121°C (250°F) and pour over the yolks while they are already foaming in the mixer.
Whip the mass at high speed until it is lukewarm (40 - 50°C, 104°F - 122°F)
If you don't use the pate a bombe right away, store it in the fridge at +4°C (+39°F), well-covered with plastic wrap.
Notes
The syrup at 121°C (250°F) placed in the mixture of yolks avoids any pathogenic contamination (such as salmonella) and makes the preparation hygienically safe.