Preheat your oven to 400°F (200°C).

Toss the raspberries with the honey and lemon juice on a parchment-lined baking sheet.

Roast the berries for 10-12 minutes until they are soft and juicy. Let them cool slightly.

Transfer the roasted berries and juices to a blender and puree until smooth. Strain through a fine-mesh sieve to remove the seeds; you should have about 3/4 cup of puree.

In a small bowl, sprinkle the gelatin over the cold water and let it sit for 5 minutes to bloom.

Warm about 1/4 cup of the raspberry puree in the microwave or on the stove (do not boil), then whisk in the bloomed gelatin until completely dissolved. Mix this back into the remaining raspberry puree.

In a large chilled bowl, whip the heavy cream, powdered sugar, and vanilla extract until stiff peaks form.

Gently fold the raspberry mixture into the whipped cream using a spatula until combined and no white streaks remain.

Spoon the mousse into serving glasses or ramekins.

Refrigerate for at least 2 hours to set before serving. Garnish with mint leaves.