Put the egg yolks, sugar, limoncello and cream in a large heat-proof bowl and lightly whisk together.
Put the bowl over a pot of simmering water. Whisk the cream mixture over low heat while the mixture froths up and thickens and the eggs are cooked, about 4 to 5 minutes. Remove from the heat and stir in the lemon zest.
Preheat the oven to 425 degrees F.
In a food processor, roughly chop the macadamia nuts. Add the remaining ingredients and pulse to blend and form a dough. Roll out the mixture between 2 sheets of parchment and cut out rounds with a 3 or 4-inch ring cutter. Put the rounds on a parchment paper lined baking sheet and bake them for 15 minutes.
In a small saucepan, over low heat, add the sugar, water and lemon rinds and simmer for 15 minutes. Drain the rinds and allow them to dry.
To serve, arrange the cakes, overlapping slightly, on a rectangular or square plate and drizzle with some sabayon sauce. Sprinkle with lemon rind and enjoy!
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.