In a large bowl, whip cream until stiff peaks form. Fold the mascarpone gently into the whipped cream, until well incorporated. Set aside.
Place half of the strawberries into the blender pitcher. Blend until smooth. Mix the remaining whole berries with the pureed strawberries in a large bowl.
Layer ⅓ of the angel food cake cubes in the bottom of a trifle or serving dish. Cover with ⅓ of the strawberries and blueberries and gently spoon ⅓ of the cream mixture over the fruit. Repeat the layers twice, ending with the cream mixture. Chill until ready to serve.
When ready to serve, run a vegetable peeler over the edge of the dark chocolate bar, letting the curls fall onto the top of the dessert.