Preheat the oven to 300°F / 150°C and grease a round metal pan with a thin layer of butter.
Place sour cream in a medium-sized bowl and beat at full speed until it turns creamy. Add sweetener while continuing to beat.
Add eggs one by one, beating continuously until the mixture gets frothy.
Add cream cheese, vanilla extract, and lime juice. Continue beating until the mixture gets smooth and creamy. Optionally, add a teaspoon of lemon zest. Add more sweetener to taste.
Pour the mixture in the pan and bake for about 45-60 minutes, until the cheesecake starts turning golden brown. DO NOT open the oven at any time!
When the cheesecake starts turning golden brown, lower the oven temperature to 210° F (100° C) and bake for another 15 minutes. Then, reduce the temperature to 120° F (50° C) and bake for 10 more minutes.
Turn the oven off. DO NOT open the oven yet. Let the cheesecake sit in the oven for another hour before opening the oven door.If you open the door too soon and the temperature falls, the cheesecake may sink in.
Cool at room temperature for 1 more hour.
Finally, put the cheesecake in the fridge for 2 hours to cool down before serving.
The topping (optional)
Using a hand electric mixer, mix together all the topping ingredients in a medium-sized bowl.
Spread over the cooled cheesecake before putting it in the fridge for 2 hours.
Optionally, decorate with lime wedges and mint leaves.
The nutritional info above includes the optional topping.