Warm up the first amount of heavy cream in the microwave until it is hot.
Cook the sugar over high heat in a small sauce pot, stirring constantly until it turns to medium amber, 170°C/338°F. Stir in the butter completely, then stir in the warm heavy cream. Remove the caramel from the heat.
Place the eggs over a hot water bath and warm them to 60°C/140°F while stirring constantly. Transfer them to the bowl of an electric mixer fitted with the whip attachment. Whip until they have cooled to room temperature. When the eggs have cooled and are still whipping, stream in the hot caramel. Add the gelatin and whip until the gelatin dissolves and the mixture has cooled to 21°C/70°F.
Whip the second amount of heavy cream in an electric mixer to medium peaks. Fold the whipped cream into the caramel base in 2 additions.