• Fill a medium deep saucepan about one-third full of water. Bring to a boil, then reduce the heat to low until barely simmering while preparing the other ingredients.
• Prepare a 9-inch square non-stick pan or other casserole dish with 3-inch high sides. Very lightly coat with vegetable cooking spray if not using a non-stick pan.
• Place the egg yolks and sugar in a heat-proof bowl and whisk to combine. The mixture will be very thick. Place the bowl with the eggs over the hot water, creating a double boiler. Don’t allow the bowl to touch the water and make sure the water is not boiling. Cook the eggs and sugar while whisking constantly, about 7-8 minutes or until thick. Remove from the heat.
• Dollop spoonfuls of the room-temperature mascarpone into the yolk mixture and stir with a rubber spatula to combine. Continue adding the mascarpone until all is incorporated. Add the vanilla and blend. If still slightly lumpy, lightly blend with an immersion blender for a second or two, but no more.
• In a clean bowl, beat the whipping cream until stiff (not dry) peaks form. Fold ⅓ of the whipped cream into the custard until incorporated. Add the remaining whipped cream and gently fold together until blended. Set aside.
• Combine the coffee and Kahlua in a shallow bowl. Quickly dip the lady fingers, one at a time into the coffee mixture, turning them over to coat the other side, then arrange in the bottom of the prepared pan. They should be touching and not overlapping. TIP: Dip each cookie quickly, counting “one-thousand one” then turn and count “one-thousand two”. This is just long enough to soak the outside of the cookie without making them mushy.
• Spoon half the custard over the bottom cookie layer. Repeat with another layer of lady fingers and the remaining custard.
• Refrigerate at least 8-hours or overnight for best results. To serve, dust with sifted all-natural unsweetened cocoa powder.

To prepare the optional topping:

• When ready to serve beat the whipping cream and powdered sugar until stiff peaks form. Top the Tiramisu with the whipped cream by pipping on top using a plain, wide decorating tip. Sift cocoa powder over the top to cover. Serve and enjoy!