Follow these straightforward steps to create your Mixed Berry Tiramisu:

1. Prepare the Berries: Wash the mixed berries thoroughly. Slice the strawberries if they are large, leaving the blueberries and raspberries whole.

2. Make the Cream Mixture: In a mixing bowl, combine the mascarpone cheese, heavy whipping cream, powdered sugar, and vanilla extract. Whip the mixture until smooth and slightly thickened.

3. Combine Coffee and Liqueur: In a shallow dish, mix the brewed espresso with coffee liqueur, if using. Let it cool slightly.

4. Soak the Ladyfingers: Quickly dip each ladyfinger into the coffee mixture, making sure not to soak them for too long. You want them moist but not soggy.

5. Layer the Ingredients: In a rectangular dish, start by placing a layer of soaked ladyfingers at the bottom. Spread half of the mascarpone mixture over the ladyfingers.

6. Add the First Layer of Berries: Sprinkle half of the mixed berries over the mascarpone layer.

7. Repeat the Layers: Top with another layer of soaked ladyfingers, followed by the remaining mascarpone mixture. Finish with the rest of the mixed berries on top.

8. Chill: Cover the dish with plastic wrap and refrigerate for a minimum of 4 hours, allowing the flavors to meld together. For best results, chill overnight.

9. Dust with Cocoa Powder: Before serving, lightly dust the top layer with cocoa powder for an added touch of flair.