Start by making the berry simple syrup. Add the water, sugar, jam and lemon juice to a saucepan. Place on the stove on medium-low heat, and cook and stir until the sugar and jam have fully dissolved. Set aside to cool down

For the Chantilly whipped cream, add the room temperature cream cheese, cold mascarpone cheese, sugar, salt and vanilla to the bowl of your stand mixer. Use the paddle attachment to whisk on medium speed for 2-3 minutes, scraping the bowl along the way, until smooth and creamy. Add the cold heavy cream, and use the balloon whisk attachment to whisk on low speed for about 2-3 more minutes, until a thick, fluffy and spreadable frosting forms. Please take care not to overmix, as that can cause the frosting to split or become grainy. Give the frosting a good stir to ensure it is well combined and not runny. Transfer a quarter of the frosting to a piping bag

Save some of the prettiest berries for decoration, and roughly chop the rest

Once the syrup has cooled down, it is time to assemble! You must assemble the cake directly on your serving stand or cake board as it cannot be transferred. Dip the ladyfingers one by one in the berry syrup (just a quick dip on both sides, don't hold) and arrange them in a neat 2x7 rectangle (see image in blog post above). Make sure they are tightly packed with no gaps between, as we are trying to form a cake layer.

Add a generous layer of the frosting on top, and carefully and gently spread it out evenly. I recommend using light pressure so you don't move the ladyfingers. Then pipe a border of the frosting around the edge of the cake, and spread a generous amount of the chopped berries in the middle. Lightly press them down

Now repeat steps 4 and 5 to add a second layer on the cake. Cover with a third layer of the ladyfingers dipped in the syrup. This is the structure of your cake

Cover the entire cake with the rest of your frosting, using an offset spatula and being as careful and gentle as you can to give the cake a neat look. If you wish, you can pipe some frosting on top for decoration

Once the cake is fully frosted, transfer to the fridge and chill for ~6 hours. This step allows the ladyfingers to soak moisture and flavor, and makes the cake layers gel together better

When you are ready to serve, decorate the cake with the berries reserved in step 3

Slice, serve and enjoy!