Prepare the Cream:

1. Whip the Cream: In a mixing bowl, whip the heavy cream with the powdered sugar and vanilla extract until stiff peaks form. This will create a light and fluffy texture.
2. Mix with Mascarpone: In another bowl, gently fold the mascarpone cheese into the whipped cream until smooth and well-combined. This creates the creamy tiramisu filling.

Prepare the Blueberry Jam Layer:

3. Thin the Jam: In a small bowl, combine the blueberry jam with 1 tablespoon of water. Stir until the jam is smooth and pourable. This will be used to add an extra layer of blueberry flavor.

Assemble the Trifle:

4. Prepare the Ladyfingers: Quickly dip each ladyfinger into a mixture of water and blueberry jam. Do not soak them for too long, as you want them to stay firm. Arrange a layer of dipped ladyfingers at the bottom of a trifle dish or large glass bowl.
5. Add the Cream Layer: Spoon a layer of the mascarpone cream mixture over the ladyfingers, spreading it out evenly.
6. Add Blueberries: Sprinkle a handful of fresh blueberries over the cream layer.
7. Repeat Layers: Continue layering the dipped ladyfingers, mascarpone cream, and blueberries until all ingredients are used up, finishing with a cream layer on top.

Chill and Garnish:

8. Chill: Cover the trifle with plastic wrap and refrigerate for at least 2 hours, or overnight, to allow the flavors to meld and the dessert to set.
9. Garnish: Before serving, dust the top of the trifle with cocoa powder and sprinkle with lemon zest (optional) for an extra pop of color and flavor.