Combine the following ingredients in saucepan over medium heat

3/4 cup sugar
2 eggs
2 tsp lemon zest

Whisk constantly for 4-5 minutes until sugar is completely dissolved and pale yellow. Remove from heat and whisk in the following:

1/3 cup Lina’s Crema di Limoncello
1/3 freshly squeezed lemon juice
3 tablespoons butter

Return to heat and continue whisking for 6-7 minutes or until mixture thickens and coats the back of a spoon.