Heat oven to 350 F (177 C). Prepare a 9-inch (23 cm) springform or cake pan
Mix flour, baking powder, and salt in a large bowl.
Whisk eggs and lemon sugar on low until mixed. Speed up to high and whip for 2-3 minutes.
Add olive oil, limoncello, lemon juice, and sour cream on low speed.
After adding all the ingredients, whisk for another minute to properly incorporate.
Pour the limoncello-lemon cake batter evenly into the pan.
After adding all the heavy cream, increase the mixer speed to medium for 2–3 minutes