Begin by whisking the chilled heavy cream in a mixing bowl until soft peaks form, making the mixture slightly thickened and slightly fluffy.
Add the sweetened condensed milk to the whipped cream and gently fold them together until well combined, maintaining the airy texture.
Stir in the lemon zest and lemon juice into the mixture, blending just until evenly incorporated. You should notice a bright, citrus aroma.
Add the chopped fresh basil leaves and fold them into the mixture, dispersing them evenly for a fragrant, speckled appearance.
Pour the creamy mixture into a freezer-safe container, smoothing out the top with a spatula to create an even surface.
Cover the container tightly with a lid or plastic wrap and place it in the freezer. Chill for at least 4 hours, or until the ice cream is firm and scoopable.
Once frozen, scoop the ice cream into bowls or cones, revealing a creamy texture dotted with vibrant lemon zest and bits of basil.