Combine the freshly squeezed lemon juice, sweetened condensed milk, and 1 cup of water in a blender. Blend until smooth and well combined, about 30-60 seconds.
Pour the mixture into a pitcher and add the remaining 2 cups of water. Stir well to combine.
Refrigerate until well chilled, at least 30 minutes for best flavor.
Fill 4 glasses with ice cubes, pour 10-ounces of the chilled creamy lemonade over the ice, and garnish with lemon slices and mint leaves if desired.
Serve immediately and enjoy
Notes
No blender? No problem! Whisk the sweetened condensed milk in a bowl, gradually adding the lemon juice while whisking constantly. Then add water and stir.
For a lower sugar version, start with 4 ounces of condensed milk and adjust to taste.
Store in the refrigerator for up to 3 days. Stir before serving as some separation may occur.
For a frozen version, blend the finished lemonade with 2 cups of ice until slushy.