Meanwhile, clean mixing bowl, then add softened and cubed cream cheese. Mix until creamy.
Add sugar, and zest, and mix to incorporate.
Mix in one egg at a time, scraping down the sides of the bowl when necessary.
Add limoncello and vanilla. Mix until well combined.
When ready, remove shortbread crust from the oven. Pour the cheesecake filling into the pan. Gently tap on the counter a few times to settle the filling.
Fill a pie tin with some water and place on the bottom shelf of the oven to create steam while the cheesecake cooks. This helps to keep the cheesecake from cracking.
Place cheesecake on the middle rack and bake at 350-degrees F. for approximately one hour, or until the cake has fully risen, and there is no indent in the center of the cheesecake. Sometimes it's necessary to turn off the heat and leave the cheesecake in the oven so that the center is fully cooked.
Remove cheesecake from the oven and leave on the counter (uncovered) until completely cool.