Celeriac, spinach, black garlic and parmesan tart

Method

1. Submerge the celeriac in cold water and give it a scrub to remove any dirt. Rinse, then put in a large saucepan and pour over enough water to cover. Mix in the vegetable stock cubes, bring to the boil, then cover and simmer for 40 minutes until nice and soft. Drain and leave to cool slightly.
2. Once cool enough to handle, top and tail the celeriac, then cut away the rough skin. Cut what’s left into roughly 1cm cubes. Heat the olive oil in a wide frying pan over a medium heat, then add the celeriac (working in batches if needed) and fry until crisp and golden all over. Set aside.
3. Heat the oven to 170°C fan/gas 5 and put a large baking sheet inside to heat up. Roll out the sheet of pastry with the paper it comes in underneath, then score a 2.5cm border around the edge of the pastry with a sharp knife and prick the centre all over with a fork. Spread the black garlic ketchup (or paste) over the centre using a spoon, leaving the border clear, then scatter over most of the spinach. Top with the celeriac cubes, then tuck the remaining spinach leaves in between. Sprinkle with the grated parmesan, season with salt and pepper, then carefully use the paper to lift the tart onto the hot baking sheet. Bake for 20 minutes, then scatter with the basil leaves and a little more parmesan to serve.