Pour orange simple syrup, non-alcoholic champagne, alcohol-free Italian spritz, and chilled soda water into the glass.
Gently stir the mixture to combine all ingredients.
Garnish with a slice of orange on the rim of the glass.
Notes
You can create your own orange simple syrup by combining equal parts water, sugar, and freshly squeezed orange juice, then heating until the sugar dissolves and letting it cool completely.