Ingredients

• 5-6 stalks rhubarb
• good shake of light brown sugar
• frozen ready-rolled all-butter puff pastry
• defrosted
• 1 tsp butter
• for greasing
• flour
• for dusting
• 2 large organic eggs
• separated
• 2 tbsp unrefined caster sugar
• 250g/9oz tub mascarpone
• 2-3 drops vanilla extract

Directions

• For the roasted rhubarb
• preheat the oven to 200C/400F/Gas 6. Cut the rhubarb into 15cm/6in or so lengths (about the length of a wooden spoon-handle) and place in a roasting tin with half a tea-cup of water and the light brown sugar. Roast until just soft enough to take the point of a knife
• about 10-15 minutes. Allow to cool
• then drain
• reserving the cooking juices.
• For the tart
• preheat the oven to 220C/425F/Gas 7. Unroll the puff pastry
• and using a rolling pin
• roll it again to make the pastry slightly thinner. Cut the pastry into three even-sized rectangles. Using a sharp knife
• score a 1.5cm/½in border around each rectangle
• being careful not to cut through the pastry. Place the pastry rectangles on a lightly greased baking sheet.
• Arrange 3-4 lengths of drained rhubarb
• depending on the thickness of them
• into the middle of the pastry rectangles and brush some of the reserved juice from the roasted rhubarb around the edges to give the pastry a shine. Bake for 20 minutes
• until golden and risen.
• Meanwhile beat the egg yolks and sugar in a bowl for a few seconds
• until thoroughly mixed. Beat in the mascarpone until you have a custard-coloured cream. Stir in a little vanilla extract; a couple of drops should be enough. With a clean whisk
• beat the egg white in a clean bowl until it stands in stiff peaks
• then fold into the creamed mascarpone mixture.
• Serve the mascarpone cream with the warm rhubarb tarts. Any remaining mascarpone cream can be served the following day with berries or used to top meringues served with fruit.