In a small saucepan, bring brewed coffee and sugar to a boil and then turn to medium heat and simmer for 5 minutes.

Doing this step first will allow it to cool while you make the rest of the cake.

Preheat oven to 350°

Prepare a 9inch square baking pan with a baking spray, or grease and flour pan.

With a bowl and whisk or with a mixer, whisk eggs and sugar until pale in color and fully blended.

Addin flour, baking powder and mix to combine.

Addin milk, butter, oil and vanilla and stir together.

Pour batter into the pan and bake for 30 minutes or until a toothpick comes out clean.

Cool in pan for 5 minutes, then turn the cake out of the pan onto a cooling rack, cool completely.

Then slice the cake in half so it's in 2 layers.

In a bowl of a double boiler (a metal bowl fitted over a saucepan of boiling water that is not touching the bottom of the bowl).

Place egg yolks and sugar in the bowl of the double boiler, reduce heat to low, and cook the mixture constantly stirring it for 10 minutes. The temperature should be 160°.

Remove from the heat and place the egg mixture in the bowl of a mixer and whip *(with a whip attachment) until thick.

Stir the Kahlua into the custard mixture.

Then allow the mixture to cool for 5-10 minutes.

Then you'll mix the mascarpone cheese into the egg mixture, beating it until creamy.

In another bowl with mixer whip the heavy cream until stiff peaks form.

Then you'll gently fold the whipped cream into the egg mixture. (Gently folding will take 5 minutes, do it very slowly, turn the mixture with a spatula a half-turn of the bowl, then stop, then do it again, rotate the bowl as needed. Do not stir it in, it will deflate and the end result will be deflated. This takes time, and it totally worth it.

Clean the cake pan.

Place the bottom layer of the cake, then slather on some coffee syrup, then spread 1/2 the custard mixture evenly.

Turn the second cake layer over and apply syrup to the cut side of the cake and place that side on top of the custard, then add syrup onto the top of the cake and then spread the remaining custard on top and smooth it evenly over cake.

Place the cake in the fridge for at least 4 hours.

Before serving dust cocoa on top. (I place the cocoa in a fine sieve and shake it over the cake).