Using a vegetable peeler remove the peel from the lemons in long strips (reserve the lemons for another use). Using a small sharp knife, trim away the white pith from the lemon peels; discard the pith.

Place the lemon peels in a 2-quart pitcher. Pour the vodka over the peels and cover with plastic wrap. Steep the lemon peels in the vodka for 4 days at room temperature.

Stir the water and sugar in a large saucepan over medium heat until the sugar dissolves, about 5 minutes. Cool completely. Pour the simple syrup over the vodka mixture. Cover and let stand at room temperature overnight.

Strain the limoncello through a mesh strainer. Discard the peels. Transfer the limoncello to bottles. Seal the bottles and refrigerate until cold, at least 4 hours and up to 1 month.

Before serving, pour prepared Limoncello and Sweetend Condensed Milk into a large pitcher. Whisk together until well combined. Serve very cold. Refrigerate remaining Creamy Limoncello.