The blackberries’ juices didn’t loosen up as much as I had hoped after letting them soak in sugar. I think in hindsight I should have probably mashed them up just a bit first, which I’ve reflected in the recipe.
2 cups heavy whipping cream
Gently smash the blackberries a couple of times with a fork, just to loosen up some of the juices. Gently toss with 1 tablespoon of the sugar and allow to sit for at least 30 minutes.
Using a hand blender, whip the cream and 1 tablespoon of sugar until stiff peaks form and you have fluffy whipped cream. Set aside in a refrigerator to chill.
Using a standing mixer or hand blender, beat the egg whites until they too have stiff peaks and are light and fluffy. Gently fold in the whipped cream.
In a small bowl combine the white chocolate chips and butter. Heat in the microwave for 30 seconds and then stir. Repeat this step until the chocolate and butter are completely melted and combined. Allow to cool slightly. (you don’t want to add the hot chocolate to the cream mixture or it will deflate the mousse, but if it cools too much the chocolate will solidify before you’re able to add it in)Gently stir in the chocolate until combine. Pour the mousse into individual serving dishes and allow to chill in the refrigerator. Or you can eat immediately, either way. Be sure to top with the berries.