For the cake: Preheat the oven to 350 degrees F. Grease and flour three 6-inch round cake pans.
Whisk together the sour cream, buttermilk, vanilla extract, almond extract and eggs in a small bowl until well blended; set aside.
In the bowl of a stand mixer fitted with a paddle attachment (or a large mixing bowl if using a hand mixer), add the cake flour, granulated sugar, baking powder and salt. Mix on low speed to combine, 30 seconds.
With the mixer on medium speed, slowly add the butter a few pieces at a time. Beat until the dry ingredients are crumbly and moistened by the butter, about 1 minute. Scrape the sides and bottom of the bowl.
Gradually add half of the egg mixture to the flour-butter mixture and beat on medium speed until the batter is thick and fluffy, 1 1/2 minutes. Scrape the sides and bottom of the bowl. Add the remaining egg mixture in 2 additions, scraping the bowl and beating for 20 seconds after each addition.
Pour the batter into the prepared pans and sharply tap the pans once on the counter to remove air bubbles. Bake until a toothpick inserted in the center comes out clean, 20 minutes. Cool the cakes in the pans on a wire rack for 10 minutes. Remove the cakes from the pans and let cool completely on the rack.
For the tiramisu syrup: Bring the sugar, water and espresso powder to a boil in a medium saucepan. Remove from the heat and stir in the coffee liqueur.
For the Tiramisu Filling: In a bowl of a stand mixer fitted with a paddle attachment (or a large mixing bowl if using a hand mixer), add the mascarpone, confectioners' sugar, coffee liqueur and vanilla extract. Mix on medium speed until well blended.
In a separate bowl of a stand mixer fitted with a whisk attachment (or a large mixing bowl if using a hand mixer), add the whipping cream and whisk until stiff peaks form. (Do not over-whisk.) Using a rubber spatula, gently fold the mascarpone mixture into the whipped cream.
For the vanilla bean Swiss meringue icing: Place the egg whites and sugar in the bowl of a stand mixture set over a saucepan of simmering water. Whisk constantly until the sugar melts and the mixture becomes very thin and warm. Remove the bowl from the heat and add the vanilla seeds. Whisk on high speed until stiff peaks form, about 5 minutes. Continue beating on low speed until cool.
Beat in the butter, a few pieces at a time, on medium speed. (The mixture may curdle before coming together.)
To assemble the cake: Using a serrated knife, level off the tops of the cake layers. Place one layer on a serving plate or board and brush some tiramisu syrup on the top. Put 1 cup of the Swiss meringue icing in a piping bag fitted with a large round tip and pipe a thin dam around the edge of the cake. Spoon a 1/2-inch layer of the tiramisu filling onto the cake and gently spread it out to the dam. Repeat with the second layer of cake. Place the final layer on top and ice the cake with the remaining Swiss meringue icing.