Add the heavy whipping cream to the bowl of a food processor. Process until stiff peaks form, for about a minute and a half, making sure to not overwhip, as it will be harder to mix later. Transfer the whipped cream to a bowl.
Return the food processor bowl to the base (no need to clean). Add the ricotta, sweetened condensed milk, orange zest, vanilla caviar and salt, if using. Process until smooth, about 2 minutes.
Using a rubber spatula, add the ricotta mixture to the bowl of whipped cream and fold in gently. Transfer to a freezeproof container with a lid and freeze until firm, at least 6 hours.
Serve topped with a few raspberries and the chopped pistachios.