To a blender, add the raspberries, lemon juice, and granulated sugar and blend until smooth.

Pour the mixture through a fine mesh sieve to remove the seeds. Make sure to press all of the liquid through the sieve. 

To a small saucepan over medium heat, add the raspberry purée and cook for 6-8 minutes, stirring frequently, until the mixture has reduced by about a third. Remove from heat and let cool slightly.

To a small pinch bowl, add the cold water and sprinkle the gelatin over the top. Stir until it's completely incorporated, then let it sit for 5 minutes. It should set completely. 

While the raspberry purée is still warm (but not hot!), stir in the gelatin until it's fully dissolved.

Optional: whisk in the freeze-dried raspberry powder (or a few drops of red food coloring) for extra intense pink color. 

In a large mixing bowl, whip the heavy cream with the powdered sugar, vanilla extract, and salt until soft-medium peaks form.

Fold ⅓ of the raspberry mixture into the whipped cream, then gently fold in the rest, mixing very gently just until no streaks of color remain.

Spoon into glasses or molds (optional: add a dusting of raspberry powder on top) and move to the refrigerator for 3 hours, until fully set.