Carrots make a great filling for a tart because they are sweet and colourful. Here the smooth and creamy filling is made with cream cheese, plus cashews for extra protein. The oats provide a nutty flavour.
To make the pastry, mix together the flour, oats and a pinch of salt, then rub in the margarine with your fingertips. Add enough of the cold water to bind to a soft dough. Wrap in plastic wrap and put in the refrigerator for 20 minutes.
Preheat the oven to 180°C, with a baking tray inside to heat up. Roll out the pastry on a lightly floured work surface to a round large enough to line a 23 cm flan tin. Gently push down into the edges of the tin and trim the edge. Prick the base with a fork, then line the pastry case with baking paper and fill with baking beans or uncooked rice.
Put the tin on the tray and bake for 20 minutes. Remove the paper and beans; bake for 3 minutes.
Meanwhile, put the carrots into a saucepan of water, bring to the boil and simmer for 8 minutes until very soft. Drain and transfer to a food processor. Purée until smooth, then add the cheese and pulse to combine, scraping the sides occasionally. Add the egg and zest and pulse a few times to mix. Season.
Pour the mixture into the pastry case and sprinkle with cashews. Bake for 18 minutes. Serve warm.