Prep the raspberries: Rinse and pat dry. In a small saucepan, combine raspberries, granulated sugar, and lemon juice. Cook over medium heat for 5–7 minutes, stirring, until the berries break down and the mixture is syrupy.

Blend and strain: Use an immersion blender or regular blender to puree the raspberry mixture until smooth. Press it through a fine-mesh sieve to remove seeds. Stir in the vanilla. Let it cool to just warm, not hot.

Bloom the gelatin (optional): Sprinkle gelatin over cold water in a small bowl. Let it sit for 5 minutes. Gently warm the bloomed gelatin in the microwave for a few seconds or over a hot water bath until melted. Whisk into the warm raspberry puree. This helps the mousse hold its shape.

Whip the cream: In a chilled bowl, whip the heavy cream with a pinch of salt to soft peaks. If you like a slightly sweeter mousse, beat in 1–2 tablespoons powdered sugar. Do not overwhip.

Whip the egg whites (optional): In a clean bowl, whip egg whites to soft peaks. Add 1 tablespoon granulated sugar and beat to medium peaks. This adds extra lift and cloud-like texture.

Fold it together: Gently fold one-third of the whipped cream into the raspberry puree to lighten it. Fold in the remaining whipped cream with broad, gentle strokes to keep it airy. If using egg whites, fold them in last, just until no streaks remain.

Portion: Spoon or pipe the mousse into cups, glasses, or small jars. Tap gently to level the surface.

Chill: Refrigerate for at least 2 hours, or until set and lightly jiggly. If using gelatin, it will firm up more distinctly.

Garnish and serve: Top with fresh raspberries, a small dollop of whipped cream, mint leaves, or a sprinkle of crushed vanilla cookies for texture.