This is a really useful recipe to have up your sleeve as not only is it impervious to human error, but you can make it throughout the year with whatever fruit's around. Pears, apples and quinces work in the colder months, or try plums, peaches, apricots or cherries when it's warmer. This is traditionally made with just almonds, but we mixed in some pistachios for colour and flavour, hazelnuts or walnuts also work well too. Either way, be prepared for a standing ovation.
For the pastry
350g plain flour
100g icing sugar
225g cold unsalted butter, cubed
3 egg yolks
For the rhubarb
2 sturdy sticks of forced rhubarb
3 tbsp caster sugar
Seeds from 1/2 vanilla pod
Zest of 1/2 orange
For the frangipane
75g shelled pistachios
150g soft unsalted butter
150g caster sugar
75g ground almonds
To make the pastry, place the flour, sugar, a pinch of salt and the butter in a food processor (or mix with your fingers tips) and blitz until the mix resembles breadcrumbs. Add the egg yolks, pulse it again a couple of times to mix them in, then check that the pastry sticks together when you grab a handful. If not, add a few drops of cold water and pulse a little more. Empty the crumbly mix into a bowl and push into a ball before flattening slightly and putting in the freezer to firm up.
Meanwhile, get the rhubarb ready for its big moment. Wash, then cut it into 4cm lengths. Place in a heat-proof bowl and toss with the sugar, vanilla seeds and orange zest. Add a splash of water, then cover tightly in clingfilm and place on top of a simmering pan of water. Leave it to tick away for the 30 minutes, occasionally giving it a gentle shake. This is a great way of cooking rhubarb as it gets poached in its own juice and doesn't fall apart on you. Have a check and if you can just stick a knife through it, it's ready - you don't want to over-cook it as it will continue to cook in its juices. Remove the clingfilm and leave to cool.
Preheat the oven to 170C/325F/Gas 3. Take the dough out the freezer, and using the coarse side of a grater, grate the pastry into a 28-cm loose-bottomed tart tin - you probably won't need all the pastry so perhaps only grate a quarter of the piece at the time. Working quickly, push the pastry against the sides of the tin with your finger tips - it doesn't need to be neat as you'll be tidying it up later. Do the base as well making sure it's about 1/2cm thick. Return to the freezer for a further 10-15 minutes until completely frozen. Once frozen, run a knife around the edge to trim off any excess pastry, prick in a few places with a fork, then place in the oven for 15-20 minutes until golden and firm to the touch. Leave to cool.
Meanwhile, make the frangipane. Place the pistachios in a food processor and grind until coarse (or chop). Put to one side, then chuck the butter and sugar into the processor (or use a wooden spoon, bowl and elbow grease) and cream together until pale, then add the nuts and a good pinch of salt. As soon as they're mixed in, add the eggs, one at a time. Spoon the frangipane into the cooled tart base and spread evenly. Arrange the rhubarb prettily on top, then place in the middle of the oven for 30-45 minutes until golden brown and just set. Leave to cool, then serve with cream.