• Half fill a medium bowl with cold water, add the gelatine sheets and leave to soften for 5 minutes.
• Put the milk and sugar into a medium saucepan. Split the vanilla pod in half length ways, scrape the seeds into the pan and add the pod too. Heat the milk very gently until the sugar dissolves and the milk is almost at simmering point, stirring with a whisk to help break up any clumps of seeds. Do not allow to boil. Turn off the heat.
• Take the softened gelatine sheets in one hand and squeeze the excess water back into the bowl. Drop the gelatine into the hot milk and stir until fully dissolved. Stir in the cream and pour the mixture carefully through a sieve into a large jug.
• Put four wide ramekins onto a small tray and set four small glass tumblers at an angle in each one, using blue tac to hold in place. Pour the cream mixture into the tumblers. Cover lightly with cling film and chill for 4 hours, or overnight, until set.

Rhubarb Compote

• Put the rhubarb into a medium non-stick frying pan. Sprinkle with the sugar and give a small shake. Place on the hob over a medium-high heat and cover with a lid or heatproof plate. Cook for 5-6 minutes or until the rhubarb is tender but still holding its shape. You can test it is ready by poking gently with a knife- it will continue cooking for a short while after you take it off the heat. Tip into a heatproof bowl and leave to cool. Cover and chill if making ahead, then add a little extra sugar to taste if needed.
• Take the panna cotta from the fridge. Stir the prosecco very lightly into the rhubarb compote and spoon on top of the panna cotta immediately before serving.