Separate the egg yolks from the whites if you haven't done this already. Discard the whites. Using a stand or electric hand mixer, beat the egg yolks and sugar together on high speed until pale-yellow in color, about 7 minutes.

Fold the mascarpone cheese into the egg yolk mixture by hand using a silicone spatula or you can use your mixer on a medium-setting to combine the mascarpone with the egg yolks and sugar. 

Turn the mixer speed-setting up and slowly add the heavy cream to the mascarpone/egg yolk mixture. Beat on high speed until stiff peaks form, about 3 minutes.  Be very careful not to over-beat as this can cause the whipped cream to collapse and separate.

Pour the espresso and rum (or vanilla) into a shallow bowl, and get your 8x8-inch glass baking dish ready. Separate the lady-fingers into 2 groups of 9.

Quickly dip the first set of lady fingers one by one in the espresso, and arrange them in a single layer on the bottom of the glass baking dish. You'll need to break some of the ladyfingers in half so they all fit.

Top the first layer dipped ladyfingers with half of the mascarpone cream mixture. Gently spread the mascarpone cream out in an even layer using an offset or silicone spatula. Spread gently so that you don't disturb the layer of ladyfingers underneath.

Dip remaining ladyfingers into the espresso and arrange them on top of the mascarpone layer.

Spread the top layer of mascarpone over the second layer of lady fingers

Cover the tiramisu with plastic wrap and refrigerate for a minimum of four hours.

Once the tiramisu has chilled, unwrap it and top it with a dusting of cocoa powder prior to serving.

Cut the tiramisu, or just scoop it out with a large spoon. Garnish with sliced strawberries and fresh mint leaves.