Brew very strong coffee or espresso and set aside.
Separate your eggs into egg white and egg yolks
Using the double boiler method, add egg yolks with 1/4 cup of sugar and whisk until smooth, light in colour and thickened. Keep whisking so your egg yolks do not clump up and cook. Set aside briefly.
In a large bowl, mix together your mascarpone, Grand Mariner, salt and vanilla.
Add your egg yolk and sugar mixture and mix well.
Add 1/4 cup of sugar into your egg whites and beat until stiff peaks form. Make sure your beaters are clean when beating your egg whites. I usually beat them first so I don't have to worry about this. They should not be dry. Set aside
In a separate bowl add your heavy whipping cream and beat until firm peaks form, do not overheat or your whipped cream will turn into butter.
Fold in your whipped cream into mascarpone, yolk and sugar mixture.
Fold in your egg whites until well combined.
Take your cooled coffee and mix in your bourbon, and quickly dip your lady fingers into it and line the bottom of your baking dish. You do not want the lady fingers soaked, just a quick dip on both sides.
Scoop half of your cream mixture on top of your coffee soaked lady fingers and smooth it out.
Repeat with another layer or lady fingers and a final top layer of your cream.
Smooth out as best as you can and you can cover with plastic wrap or tin foil and place in fridge for at least 12 hours before finishing off with cocoa powder and eating.
I usually sprinkle with cocoa powder before allowing to set, and sprinkle with a mother dusting of cocoa powder before serving. Note: The covering your tiramisu, especially if you have sprinkled before setting, try and avoid touching the surface with plastic wrap or foil as this will remove your cocoa layer. This may be difficult to avoid if the dish you are using is not too deep.
Slice and enjoy after it has set.