Prep Your Pan: Gently line an 8x4 inch loaf pan with plastic wrap, making sure to leave some overhang on all sides. This simple step makes unmolding your dessert incredibly easy later on!
Whip It Up Light: In a large mixing bowl, beat the cold sour cream with an electric mixer on medium speed until it's smooth, which takes about 1 minute. Next, gradually add the confectioners' sugar, beating until everything is just combined. Reduce the mixer speed to low and slowly pour in the cold heavy cream. Increase the speed back to medium and continue beating until beautiful stiff peaks form, typically within 2 to 3 minutes. This creates your light and airy semifreddo base.
Fold & Freeze: Carefully fold in the chopped pistachios and about half (1 pint or 2 cups) of the fresh raspberries into your creamy mixture. Gently spoon this delightful blend into your prepared loaf pan. Place it in the freezer for at least 4 hours, or until it's perfectly firm and set. You can even prepare this ahead of time and keep it frozen for up to a week!
Berry Drizzle & Serve: While your semifreddo is chilling, whisk together the fresh lemon juice and pure honey in a small bowl until the honey is fully dissolved, creating a light, sweet glaze. Add the remaining raspberries to this mixture and toss gently to coat. Let them sit for about 18-20 minutes, stirring occasionally, to allow the flavors to meld. When you're ready to serve, carefully invert the frozen semifreddo onto a lovely platter and remove the plastic wrap. Spoon the honey-lemon raspberries over the top and garnish with fresh mint leaves for a final touch of elegance. Enjoy this simple, elegant treat!