Heat the cream, milk and a pinch of salt in a medium sized saucepan over medium high heat. Bring to a simmer and reduce heat.
Meanwhile, in a separate bowl, whisk the egg yolks and gradually add the sugar and continue whisking to combine.
Temper the cream mixture into the eggs and sugar by gradually adding small amounts. Add 1/3 of a cup of the cream at a time until just about all of the cream has been added to the eggs.
Return the entire egg-milk mixture to the saucepan with the remaining milk and reheat.
Add 1/2 cup of limoncello and stir well.
Continue to cook, stirring frequently, until the mixture thickens and coats the back of the spoon and reaches 170 degrees F .
Pour the mixture into a bowl and allow to sit at room temperature for about 30 minutes. Place the bowl in the refrigerator, cover and store for at least 4 hours.
Remove from the refrigerator and pour into the ice cream maker and process according to manufacturer's directions. This process should take approximately 20-30 minutes. Serve as is for soft serve or place in the freezer and allow the ice cream to harden for a couple of hours.