Step 1: In a large bowl, use a hand mixer to beat the heavy cream, powdered sugar, and vanilla until they form medium peaks.
Step 2: In another bowl, combine the mascarpone with about 1/4 cup of the whipped cream. Stir until mixed, then gently fold in the rest of the whipped cream.
Step 3: In a large glass measuring cup, mix the coffee and Grand Marnier.
Step 4: Spread a thin layer of whipped cream at the bottom of a large trifle dish. Dip each ladyfinger quickly into the coffee mixture, then arrange them in the dish to cover the bottom. Spread about a third of the whipped cream over the ladyfingers evenly. Add half of the raspberry jam gently over the whipped cream, followed by a circle of raspberries. Repeat with another layer of ladyfingers, whipped cream, jam, and raspberries. Finish with a final layer of ladyfingers and whipped cream.
Step 5: Cover the dish with plastic wrap and refrigerate for at least 4 hours or overnight.
Step 6: Before serving, sprinkle chocolate shavings on top.