You can get rhubarb cordial online and it's worth tracking down for this really special twist on a Prosecco cocktail
Preheat your oven to 180°C/350°F. Using a mandolin or peeler, thinly slice the rhubarb lengthways, then place on a baking tray and sprinkle with the sugar. Bake for 10–12 minutes until soft, then transfer to a plate to cool. A few minutes before serving, place 2 rhubarb strips in each glass, cover with rhubarb syrup or cordial and allow to macerate for a few minutes. Top up each glass with chilled Prosecco and serve.