Add water and sugar to a saucepan and heat over low heat, stirring occasionally with a wooden spoon. Use a kitchen thermometer to monitor the temperature of the syrup, bringing it to 121°C (250 °F).
Once the syrup reaches around 115 °C (239 °F), begin whipping the egg yolks.
Once the syrup reaches 121 °C (250 °F), slowly pour it into the whipped egg yolks while continually whisking until the mixture is thick and frothy and has cooled. This is pâte à bombe, the base for pastry making.
At this point, incorporate the mascarpone and mix well with a spatula until smooth cream forms.
Use the mascarpone cream immediately in your favorite dessert. Or you may also portion the cream into small glass cups, covering each with plastic wrap. Allow the desserts to chill in the refrigerator for 2–3 hours to achieve a thicker, set consistency.
When ready to serve, consider decorating the tops with chocolate chips or a dusting of unsweetened cocoa powder for extra visual appeal and flavor.