Begin by gathering all your ingredients for the Raspberry Pistachio Mousse Cakes. Gently cleanse the fresh raspberries under cold running water, taking care not to crush them. Pat them dry with a clean kitchen towel. If you're using a cake base, ensure it's ready for layering.

In a large mixing bowl, pour in the heavy cream, then add the granulated sugar and vanilla extract. Using an electric mixer, whip the mixture on medium speed until soft peaks form—this should take about 2-4 minutes. Be cautious not to overwhip.

In a small bowl, dissolve the unflavored gelatin powder in warm water according to the package instructions. Stir gently until fully dissolved, about 2-3 minutes, then let it cool slightly.

Once the gelatin has cooled, carefully fold it into the whipped cream mixture. Use a spatula to gently incorporate the gelatin.

Gently fold in the crushed raspberries and finely chopped pistachios into the mousse blend, using a gentle hand to avoid deflating the whipped cream.

If you're using a cake base, cut it into desired shapes to fit your serving dishes. Layer it at the bottom of each dish, then spoon a generous amount of the raspberry pistachio mousse on top.

Carefully place your assembled Raspberry Pistachio Mousse Cakes in the refrigerator and let them chill for at least 4 hours, or until fully set.

Once set, remove the mousse cakes from the fridge. For a beautiful presentation, garnish each with additional crushed pistachios and a few fresh raspberries on top.