Add some water to the cooking pan and bring the water to the boil.
Then add the eggs to the heat resistant bowl. As soon as the water is cooking, you can place the bowl on top of the pan. Make sure the bowl doesn't touch the water, and that you keep whisking. The easiest way is to use an electric handmixer. Whisk the eggs until it is a pale yellow color and doesn't have any big bubbles anymore. At that point, you can add the sugar.
Take the bowl off the heat, and whisk it for another 5 minutes.
In the meanwhile, soak the gelatin sheet in some cold water.
Add the mascarpone to the egg mixture, but add it spoon by spoon. When this is nicely mixed, you can start to cook the gelatin sheet. Add the gelatin sheet with 2 tablespoons of water to pan, and place on a medium heat. As soon as the gelatin sheet dissolved in the water, you can pour the gelatin into your mascarpone mixture. Whisk during this process to make sure the gelatin dissolves evenly.