In a small bowl, bring Water (6 fluid ounce) to a boil and add in Instant Espresso Powder (2 teaspoon). Whisk until dissolved and add in Kahlua (50 milliliter). Set aside to cool.
Separate Egg (6) Yolks and set aside.
In a double boiler or bain marie, combine Egg Yolks, Caster Sugar (1 cup) and Milk (2 tablespoon). While whisking constantly, cook for 8-10 minutes to cook the egg yolks. Mixture should be smooth but not all sugar will dissolve. This is okay. Set aside and let cool.
Once cool, transfer to a large bowl and add in room temperature Mascarpone Cheese (8 ounce). Mix well until smooth.
In a stand mixer or large bowl with a hand mixer, combine Heavy Whipping Cream (1 1/2 cup) and Vanilla Extract (1 teaspoon) and mix on medium-high speed until a stiff whipped cream is made. Be careful as to not mix too long or you'll get butter. Add to cooled egg and mascarpone mixture and fold gently to incorporate.
To assemble the tiramisu, dunk Ladyfingers (7 ounce) into espresso mixture for 2-3 seconds and line the bottom of a 9"x9" baking dish with them.
Spread half of mascarpone mixture on top, repeat another layer of soaked ladyfingers and then spread remainder of mascarpone mixture on top.
Cover and refrigerate for AT LEAST 8 hours! It's best to let sit 24-48 hours. To serve, slice and plate and dust the top with Unsweetened Cocoa Powder (to taste). Enjoy!