• Step 1: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
• Step 2: In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
• Step 3: In a large bowl, beat the egg yolks and granulated sugar together until light and fluffy, about 3-5 minutes. Gradually add in the espresso (or coffee) and rum/Kahlua, if using, and mix until well combined.
• Step 4: In a separate bowl, beat the egg whites until stiff peaks form. Gently fold the egg whites into the yolk mixture in two to three additions until fully incorporated.
• Step 5: Fold the dry ingredients into the batter in two to three additions, being careful not to overmix.
• Step 6: Evenly divide the batter between the prepared cake pans and bake for 18-22 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes, then transfer to a wire rack to cool completely.
• Step 7: In a large bowl, beat the mascarpone cheese, confectioners’ sugar, and vanilla extract until smooth and creamy.
• Step 8: Once the cakes have cooled, use a serrated knife to slice each cake horizontally into two even layers, creating four layers total.
• Step 9: Place one cake layer on your serving platter or cake stand. Spread a layer of the mascarpone cream over the top. Repeat with the remaining cake layers and mascarpone cream, ending with a cake layer on top.
• Step 10: Dust the top of the tiramisu cake with a generous amount of unsweetened cocoa powder.