Prep your cups and ingredients. Set out 6–8 small dessert cups or tumblers. Finely chop all three chocolates and place each in a separate heatproof bowl. Keep your heavy cream chilled.

Bloom the gelatin (optional). Sprinkle gelatin over 2 tablespoons of cold milk in a small bowl. Let sit 5 minutes. This step helps layers slice cleanly and hold up longer on warm days.

Make the dark chocolate base. Warm 1/4 cup milk until steaming (not boiling). Stir in espresso powder and bloomed gelatin, if using, until dissolved. Pour over the dark chocolate with a pinch of salt. Let sit 1 minute, then whisk until smooth and glossy.

Whip the cream. In a chilled bowl, beat 2/3 cup heavy cream to soft peaks. It should hold a gentle curl on the whisk. Do not overwhip.

Fold to finish the dark layer. Whisk 1–2 tablespoons of the whipped cream into the melted dark chocolate to lighten it. Then gently fold in the rest with a spatula until no streaks remain.

Fill the cups. Spoon or pipe the dark mousse evenly into each cup as the first layer. Tap cups gently to level. Chill 15–20 minutes, or until the surface is slightly set.

Prepare the milk chocolate layer. Repeat the melting process with 1/4 cup warm milk, pinch of salt, and the chopped milk chocolate. If you didn’t use gelatin earlier, you can skip it here too. Whip another 2/3 cup cream to soft peaks, then fold into the melted milk chocolate as before.

Layer and chill again. Spoon or pipe the milk chocolate mousse on top of the set dark layer. Smooth gently. Chill 15–20 minutes to help it hold its shape.

Make the white chocolate layer. Warm the remaining milk (2 tablespoons). Pour over the white chocolate with a pinch of salt and vanilla. Let sit 1 minute, then whisk smooth. Taste; if you prefer it less sweet, add a tiny pinch more salt. If you want it sweeter or stiffer, sift in 1 tablespoon powdered sugar.

Fold in the final whipped cream. Whip the last 2/3 cup cream to soft peaks. Fold into the white chocolate mixture until silky and uniform.

Finish the cups. Add the white chocolate mousse as the top layer. Smooth the surface or make rustic swirls with a spoon. Chill at least 1–2 hours, or until fully set and spoonable.

Garnish and serve. Top with chocolate curls, a dusting of cocoa, or a few berries. Serve chilled with small spoons.