Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans. In a large mixing bowl, sift together the flour, cocoa powder, sugar, baking powder, baking soda, and salt. In another bowl, whisk the eggs, milk, oil, and vanilla extract until smooth.
Gradually add the wet ingredients to the dry ingredients and mix well. Finally, carefully stir in the boiling water—this makes the batter thin, but it helps create a moist cake.
Pour the batter evenly into the prepared pans. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Remove from oven and let cakes cool in pans for 10 minutes before transferring to a cooling rack.
While the cakes cool, beat the mascarpone cheese with powdered sugar and vanilla extract until smooth. In a separate bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the mascarpone mixture to create a fluffy tiramisu cream.
Mix the cooled brewed coffee and coffee liqueur in a shallow bowl. This soak will give the cake that authentic tiramisu coffee flavor.
Once the cakes are completely cool, use a skewer or toothpick to poke holes all over the surface of each cake layer. Brush generously with the coffee soak, allowing it to seep deep into the cake.
Spread half of the tiramisu cream over the first cake layer. Place the second cake layer on top and repeat with the coffee soak and the remaining cream.
Refrigerate the assembled cake for at least 3 hours or overnight to allow flavors to meld beautifully. Before serving, dust the top with cocoa powder and garnish with chocolate shavings or curls for that extra wow factor.