Barefoot Contessa (en-US)

1½ cups good vodka, such as Grey Goose
1 cup freshly squeezed lemon juice (6 lemons)
6 tablespoons sugar syrup
¼ cup Italian Limoncello liqueur
1½ cups cold club soda, such as Pelligrino
Ice cubes
Sliced lemon, for serving

Combine the vodka, lemon juice, sugar syrup, and Limoncello in a large pitcher. Just before serving, pour in the club soda and stir. Fill highball glasses with ice and pour the mixture over the ice. Garnish each drink with a slice of lemon and serve cold.

Limoncello Vodka Collins