Metal loaf pan (4 1/2 x 8 1/2 inches, measured across the top), hand mixer

• 3⁄4 cup strong brewed coffee (6 oz / 170g)
• 1⁄4 cup Kahlúa (2.3 oz / 65g)
• 3 large egg yolks (1.6 oz / 45g), at room temperature
• 1⁄4 cup sugar (1.8 oz / 50g)
• 2 teaspoons instant coffee granules
• 1 teaspoon vanilla extract
• 1⁄2 teaspoon Diamond Crystal kosher salt or 1⁄4 teaspoon Morton kosher salt
• 1/4 cup water
• 1 cup mascarpone cheese (8.5 oz / 240g), chilled
• 11⁄2 cups heavy cream (12.7 oz / 360g), chilled, divided
• 1 (7 oz / 200g) package ladyfingers or savoiardi
• Unsweetened cocoa powder, for sprinkling

1. Line a loaf pan with plastic wrap. Lightly wet the pan, and that will help the plastic to stick.
2. For the soak, combine 3/4 cup room temperature brewed coffee, 1/4 cup Kahlúa in shallow bowl, set asside.
3. Add egg yolks to medium bowl.
4. In small sauce pan, combine sugar, instant coffee, salt, vanilla extract, and water.
5. Bring sauce to boil, stirring while sugar and coffee disolve.
6. Slowly stream the still hot coffee syrup into the egg yolks while beating on medium speed.
7. Once all syrup is incorporated, turn up speed to medium high, and beat until it has a light, thick, and mousse-y texture and has cooled to room temperature. About 3 minutes. Set aside.
8. Combine mascarpone cheese and 1/2 cup heavy cream in large bowl. Whip until firm peaks. Start on low speed and work up.
9. Scrape yolk mixture into mascarpone mixture. Whip starting on low, working up until stiff peaks form.
10. If needed, trim ladyfingers to fit in bottom of loaf pan. set aside.
11. Add 1/2 cup filling to bottom of loaf pan.
12. Quickly dunk the trimmed ladyfingers, one at a time, into the coffee-Kahlua soak, then place them crosswise in a row in the pan.
13. Scrape a level 1 cup of the filling over the ladyfingers in the pan, spreading it in an even layer.
14. Repeat the trimming, dipping, and arranging process for a second layer of ladyfingers.
15. Srape another level 1 cup of the filling over the second layer of ladyfingers in the pan, spreading it in an even layer.
16. Add a third crosswise layer of dipped ladyfingers, noting that you won't have to trim them this time because the top of the pan is wider than the base.
17. Smooth remaining amount of filling on top of ladyfingers.
18. Take overhang of plastic and wrap and gently press on top of the filling.
19. Refrigerate until the filling is set and the ladyfingers are completely softened, at least 12 hours.
20. Remove set cake from refrigerator.
21. Whip remaining 1 cup heavy cream to medium peaks.
22. Unwrap top of cake, invert a serving platter, and turn out cake. Peel away plastic.
23. Cover cake in whipped cream, spread down and around the sides, covering the whole cake.
24. Lightly dust with cocoa powder.
25. Slice and serve.

source: https://youtu.be/gIdsExROADQ