In a small saucepan, combine 1/2 cup of water and 3/4 cup of granulated sugar. Heat over medium heat, stirring occasionally, until the sugar is completely dissolved.
In a pitcher, muddle 1 cup of fresh basil leaves with a wooden spoon. Add the dissolved sugar mixture and 1 cup of fresh lemon juice.
Stir in 3 1/2 cups of water and mix until well combined.
If desired, strain the lemonade through a fine-mesh strainer to remove any bits of basil.
Serve the basil lemonade in glasses filled with ice. Garnish with additional basil leaves if desired.
Notes
For a sweeter lemonade, add more sugar to taste.For a less sweet lemonade, reduce the amount of sugar or use a sugar substitute.For an adult version, add a splash of vodka to each glass.