- Pour the water into a medium heatproof bowl and add unflavored gelatin. Stir and let it sit until the mixture puffs up, about 2 minutes. Fill a small saucepan, that can hold the heatproof bowl, with a couple inches of water and bring to a simmer. Place the bowl with gelatin on top, stirring occasionally, until gelatin completely dissolves, about 2 minutes. Remove from heat. 
- Add the milk and Dulce de Leche to a small saucepan set over medium heat. Stir until fully combined, about 1 to 2 minutes.  
- Pour the mixture into the bowl with the diluted gelatin and mix well. Set the bowl over an ice bath and let mixture cool and begin to set. 
- In a stand mixer, fitted with the whisk attachment, beat the heavy whipping cream until it holds soft peaks. Be careful not to overbeat. 
- Gently fold the cooled dulce de leche caramel mixture into the whipped cream until fully combined. Don’t overmix, so you won’t lose much volume. Pour the mixture into a 6 cup ring mold, bundt pan, or 6 individual ramekins (of 6 to 7 ounces). Cover with plastic wrap and chill for at least 2 to 3 hours before serving. 
- When ready to serve, remove mousse from refrigerator. If using a mold or bundt pan, invert the mousse onto a platter. Top with berries, if desired, or chocolate salami.