20 to 24 ladyfingers (from a 7-ounce package), broken into 1-inch pieces
3/4 pound blueberries (2 1/2 cups)
In a medium bowl, combine raspberries with 1/4 cup confectioners' sugar and orange juice. With the back of a fork, lightly mash berries to release their juices and let sit 10 minutes. Meanwhile, in a large bowl, stir together mascarpone and 1/2 cup confectioners' sugar until smooth. Whisk in cream, vanilla, and pinch of salt and whisk until soft peaks form, about 4 minutes.
Cut one or two pieces parchment 1 inch taller than side of an 8-inch springform pan and line inside of pan. Place half the ladyfingers in pan and top with half the raspberry mixture. With a small offset or rubber spatula, spread half the whipped cream over berries. Tap pan gently on counter to remove air bubbles. Repeat with remaining ladyfingers, raspberry mixture, and whipped cream.
Top with blueberries and refrigerate until whipped cream is stiff and cookies have softened, about 3 hours (or, tightly covered with plastic, up to 3 days). To serve, unmold trifle and peel away parchment.
We used cake sparklers on this trifle. They should only be used outdoors, according to package instructions; alternatively, look for sparkle candles, which will give you a similar look. Both are available from many online baking-supply stores.