Prepare simple syrup by combining 1 c. water and 1/2 c. sugar in a small saucepan. Bring to a boil; once boiling,remove from heat and add juice of 1 lemon and fresh basil leaves.
Set aside to cool.
In a large pitcher, combine champagne, orange juice, and 1/3 c. cooled lemon basil simple syrup.
Garnish with orange and lemon slices and fresh basil.