Let’s create this sophisticated Tiramisu Cake! First, prepare the oven and pans. Preheat oven to 160°C fan / 180°C conventional / 350°F. Lightly grease and line the bottoms (and optionally sides) of two 6-inch round cake tins (preferably loose-bottomed). If you have four tins and oven space, prepare all four.

Prepare the cake batter using one of the methods below:

• Food Processor Method: Place the room temperature butter, sugar, flour, baking powder, and salt into the food processor bowl. Pulse a few times until combined into coarse crumbs. Add the room temperature eggs one by one, pulsing just 1-3 times after each egg. Add the room temperature milk and vanilla seeds (or extract/paste). Process briefly, only until just combined. Do not overmix.
• Hand/Stand Mixer Method: In a medium bowl, whisk together the flour, baking powder, and salt. In a large bowl (or stand mixer bowl with paddle), cream the room temperature butter and sugar together on medium-high speed for 3-5 minutes until light, pale, and fluffy. Beat in the room temperature eggs one by one, adding a spoonful of the flour mixture after each egg (this helps prevent curdling). Beat in the room temperature milk and vanilla seeds (or extract/paste). On low speed, gradually mix in the remaining flour mixture until just smooth. Do not beat for more than 30 seconds after flour is added.

(Optional) Making Colored/Flavored Layers: Weigh the total batter (recipe example: 1150g). Divide it into three portions: half for coffee (e.g., 575g), one quarter for chocolate (e.g., 287g), and one quarter plain vanilla (e.g., 287g). Gently fold the 1 ½ tablespoon espresso powder into the largest portion. Gently fold the 1 ½ tablespoon cocoa powder into one of the smaller portions. Leave the last portion plain. If not making flavored layers, simply keep the batter as one batch (plain vanilla).

Bake the cakes. If making flavored layers and using only two tins: Divide the coffee batter between the two prepared tins, leveling the tops. Bake for about 25 minutes, or until a skewer inserted into the center comes out clean. Let cool in the tins for 5 minutes, then carefully remove (pushing up loose bottoms if using) and transfer to a wire rack to cool completely. Clean, grease, and line the tins again. Pour the vanilla batter into one and the chocolate batter into the other. Bake for 25 minutes or until done. Cool as before. (If you have four tins, divide the coffee batter between two, vanilla in one, chocolate in one, and bake all, possibly in batches depending on oven). If making plain vanilla layers, divide the entire unflavored batter between four tins (or bake in two batches of two) for 25 minutes each, or divide between two tins and bake longer (approx. 40-50 mins, check carefully), then split horizontally later. Recipe implies baking 4 layers regardless of flavoring.

While cakes cool, make the Coffee Syrup. Place the 2 tablespoons espresso powder, ½ cup sugar, and ½ cup water into a small saucepan. Bring the mixture to a boil over medium heat, stirring until the sugar has completely dissolved. Remove from heat and let the syrup cool completely.

Prepare the Mascarpone Frosting. Place the cool but slightly softened mascarpone into a large bowl. Add the sifted icing sugar, 1 tablespoon of milk, and the vanilla seeds (or extract/paste). Using a spatula initially, gently stir and fold the ingredients together until the mixture is smooth and combined. Be very careful not to overmix, as mascarpone can split easily. Add up to 1 more tablespoon of milk only if needed to reach a smooth, soft, spreadable consistency.

(Optional) Flavoring Frosting for Ombre: Separate off two smaller portions of the frosting (about 125g / roughly 1/2 cup each) into two separate small bowls. Leave the majority of the vanilla frosting in the main bowl. Melt the 25g of dark chocolate gently (microwave or double boiler) and let it cool for a minute until barely warm. Stir the melted chocolate into one of the smaller frosting portions until combined. Stir the 1 teaspoon of espresso powder into the other smaller frosting portion until combined. You now have vanilla, chocolate, and coffee flavored frostings.

Assemble the Tiramisu Cake. Ensure cake layers are completely cool. If they have domed tops, level them carefully with a long serrated knife. Place one cake layer onto your cake board, stand, or serving plate (a turntable is helpful). Using a pastry brush, generously soak the top of the layer with the cooled coffee syrup. Let it soak in.

If using flavored layers, the suggested order is: chocolate cake base, vanilla frosting, coffee cake, vanilla frosting, second coffee cake, vanilla frosting, vanilla cake top. Spread about ⅓ cup of the vanilla mascarpone frosting evenly over the first soaked layer. Carefully place the next cake layer on top, soak it with syrup, and spread with another ⅓ cup vanilla frosting. Repeat with the third layer. Place the fourth and final layer on top and soak it with syrup.

Apply a very thin layer (crumb coat) of the vanilla frosting all over the outside (top and sides) of the cake. This traps crumbs and provides a base. Place the cake in the refrigerator for 15-20 minutes to set the crumb coat.

(Optional) Creating the Ombre Frosting: Apply the flavored frostings to the sides of the chilled cake. Start with the chocolate frosting, applying it roughly to the bottom quarter of the cake’s height. Apply the coffee frosting to the next quarter up, slightly overlapping the chocolate layer. Cover the remaining upper half and the top of the cake roughly with the vanilla frosting. You’ll likely have leftover frosting. Using a bench scraper or large offset spatula held vertically against the side of the cake, rotate the turntable (or carefully turn the plate) to smooth the frosting, blending the color transitions gently to create the ombre effect. Smooth the top edge. (Alternatively, frost the entire cake smoothly with vanilla frosting for a classic look).

Finish the cake with a generous dusting of unsweetened cocoa powder all over the top, using a fine-mesh sieve for an even coating. Chill the cake for at least 30-60 minutes before slicing to allow the frosting to firm up slightly. Remember to let slices sit out briefly before serving.