Prosecco and peach juice. It should be white peach juice. The juice was canned and called Kerns. And is mostly not awful stuff, apart from the corn syrup, of course. But it's not going to kill you. Not in this drink. I'd like to find better peach juice, though. I suspect it will have to be imported and Italian.
When peach time rolls round, puree a batch of very ripe fruit, strain, and refrigerate for adding to your bubbly.