Hydrate unflavored gelatin by sprinkling it over cold water. Let it sit for about 10 minutes until it absorbs the water and softens.

Blend fresh raspberries until smooth, then strain to remove seeds. Warm a quarter of the puree gently, then stir in the bloomed gelatin until dissolved.

In a mixing bowl, whisk together the gelatin-raspberry blend with fresh lemon juice.

In a chilled bowl, beat the heavy cream until stiff peaks form.

Whip egg whites until foamy. Gradually add granulated sugar, then heat sugar with water to 246ºF. Pour this syrup into the egg whites while continuing to whip until glossy peaks form.

Gently combine the whipped cream and meringue, preserving the airiness. Add the raspberry puree in two parts, folding carefully until fully incorporated.

Spoon the mousse into serving glasses or bowls. Refrigerate for several hours or overnight until set.

Heat any remaining raspberry puree with a dash of sugar and a bit of lemon zest. Cool it down before drizzling it over the mousse.