Add the chilled heavy cream to a large mixing bowl and whisk until soft peaks form, creating a light and airy base.
Gently fold in the sweetened condensed milk, blending until the mixture is smooth and uniform, with a creamy texture.
Stir in the lemon zest and chopped basil leaves, distributing them evenly throughout the mixture and adding specks of green and yellow.
Add the freshly squeezed lemon juice and gently mix to incorporate, brightening the flavor and slightly thinning the mixture.
Pour the mixture into a freezer-safe container, smoothing the top with a spatula for an even surface.
Cover the container tightly with plastic wrap or a lid, then freeze for at least 4 hours or until firm and scoopable.
Once frozen, scoop the ice cream into bowls or cones. The final texture should be creamy with visible flecks of basil and lemon zest for a fresh, herbal touch.