Step 1

Preheat oven to 350 degreees.

Step 2

In bowl, whisk together the flour, baking powder, and salt; set aside.

Step 3

In a large mixing bowl, use a handheld mixer to beat together the sugar and butter until pale in color; about 2 minutes. Beat in the eggs, one at a time, until combined. Stir in the vanilla.

Step 4

Working in batches, add in 1/3 of the flour mixture followed by 1/2 of the milk. Continue until all of the flour and milk has been incorporated into the batter. Use a rubber spatula to scrape down the bowl and make sure that everything is evenly combined.

Step 5

Spray your bundt cake pan with nonstick cooking spray. Pour in the batter and smooth using a rubber spatula. Bake for about 50 minutes, or until a toothpick inserted in the cake comes out clean.

Step 6

Remove the cake from oven and let cool in pan for 5 minutes. Then carefully flip the pan over on to a cooling rack and let cool for another 5 minutes until the cake releases from the pan. Let the cake cool completely (you can also chill the cake to speed up the cooling or make a day in advance.)

Step 7

One the cake is completely cooled, use a serrated knife to carefully cut the top of the cake about a third of the way down from the top. Carefully remove the top and set aside on a plate.

Step 8

In a bowl, stir together the espresso granules and sugar. Carefully pour in the boiling water and whisk until the sugar and espresso have dissolved. Stir in the Kahlua.

Step 9

Use a pastry brush to brush the espresso mixture over the cut bottom side of the bundt cake. Continue until all of the mixture has been absorbed by the cake. Set aside.

Step 10

In a bowl, use a handheld mixer to combine the mascarpone, powdered sugar, Kahlua, and vanilla; set aside.

Step 11

In a seperate bowl, use the handheld mixer to beat the heavy cream until firm peaks form; about 4 minutes.

Step 12

Using a rubber spatula, gently fold the whipped cream into the mascarpone mixture in two batches being careful not to overmix.

Step 13

Spread the tiramius filling over the bottom half of the bundt cake. Use as much tiramsu filling as you like (leftover filling is great for topping fruit).

Step 14

Carefully place the top half of the bundt cake over the bottom.

Step 15

In a bowl, use a handheld mixer to mix together the mascarpone and butter. Stir in the Kahlua. Add in the powdered sugar and continue mixing until the frosting is smooth. (If the frosting is too thick, add a teaspoon of milk to thin it out). Drizzle the frosting over the top of the bundt cake.

Step 16

Place the cocoa powder in a fine mesh sieve and dust over the top of the cake.