In a medium bowl, combine boiling water with instant espresso coffee; stir until coffee granules are completely dissolved. Add Tia Maria and quickly stir; set aside.
In a double boiler, place egg yolks and whisk constantly until fluffy before adding sugar. Whisk continuously and when it gets thick, add half of Marsala wine; continue whisking until smoother. Add the remaining liqueur and whisk until tiny bubbles form on the surface and the mixture gets smooth and thick. Remove from heat to cool completely and transfer to a large mixing bowl.
In a very cold bowl of a stand mixer, combine cold heavy cream, sugar and vanilla. Process until stiff peaks form; set aside.
Back to egg mixture; add mascarpone and mix until well combined. Once nice and smooth, add whipped cream and fold gently (don’t deflate whipped cream) until nicely blended.
To assemble Tiramisu, dip ladyfingers in the espresso mixture for a few seconds – don’t let them sit too long otherwise they will soak up and get soggy. Place them next to each other in a 10 X 10-inch baking dish until bottom is filled. Scoop half the mascarpone mixture and using an angled spatula, smooth it out. Repeat with another layer of lady fingers followed with cheese mixture. Before spooning the mascarpone mixture, gently press on the lady fingers to even them out. Make sure to spread cheese mixture evenly.
Cover with plastic wrap or foil and transfer to the refrigerator for 8 to 48 hours. When time to serve, place a piece on a serving plate and dust with 1 teaspoons cocoa powder using a small sieve.