Combine Ingredients: In a mixing bowl, combine the Greek yogurt, sugar substitute, lemon juice, and lemon zest.
Mix Well: Whisk the mixture until it’s smooth and well combined. The goal is to achieve a creamy consistency!
Pour into Mold: Line a loaf pan with plastic wrap. Pour the yogurt mixture into the prepared pan, spreading it evenly.
Freeze: Cover with additional plastic wrap and freeze for at least 4 hours, or until the semifreddo is firm.
Servings: When ready to serve, remove the semifreddo from the freezer and let it sit for a few minutes at room temperature. Slice and enjoy your refreshing dessert!