Here’s the recipe, just in case you need it:
1.5 ounces Campari
1.5 ounces sweet vermouth
1.5 ounces prosecco
Add the Campari and sweet vermouth into a mixing glass with ice and stir. Add prosecco and stir again, then strain into a champagne flute. Alternatively, strain into a rocks glass with ice. Garnish with orange peel or slice. Top with more prosecco for added sweetness, to taste.
Source: https://www.buzzfeed.com/andyneuenschwander/negroni-sbagliato-with-prosecco-in-it-recipe