Start by preheating your oven to 350°F (175°C). In a large bowl, combine the melted butter and espresso-flavored liqueur. You can’t rush a good thing, so let it sit for a few minutes to meld.

Line a baking dish with the ladyfinger biscuits, arranging them in a single layer. Pour the butter mixture over the ladyfingers, ensuring they soak it up nicely. This will lay the groundwork for your dessert.

In a separate bowl, beat the cream cheese and mascarpone until light and fluffy. Add the sugar and blend until fully combined. Take a moment to admire that velvety texture—it's a thing of beauty.

Slowly add the eggs, one at a time, making sure they’re fully incorporated before adding the next. Don’t forget to scrape down the sides of the bowl to gather all that goodness.

Stir in the flour, coffee liqueur, sour cream, and vanilla extract. This is when the magic really happens. The mixture will become smooth and creamy, perfect for layering.

Pour half of the mascarpone filling over the ladyfingers in your baking dish. Spread it evenly. Layer the remaining ladyfingers on top, and then pour the rest of the filling over them. Smooth it out to create a beautiful surface.

Refrigerate the dessert for at least 4 hours, or overnight if you can. This step is crucial. It allows the flavors to meld together and the texture to set perfectly.

Right before serving, grate some bittersweet chocolate over the top for a beautiful finish. It adds that last touch of sophistication. Cut into squares and watch everyone’s eyes light up.