Line your tatin pan with a circle of baking paper the same diameter as the base; this makes it easier to turn the tarte out and keep the form of the vegetables. I’ve used puff here but flaky shortcrust pastry will also work well. I have made this with all sorts of root veg, such as carrots, celeriac and fennel, so you have plenty of options and can experiment to your taste.
Put the pastry on a lightly floured kitchen bench and roll it out into a disc 4 mm (1⁄8 in) thick, then cut a circle 1 cm (1⁄2 in) wider than your pan. I use a 25 cm (10 in) round tarte tatin pan. Lay the pastry between two sheets of baking paper and refrigerate until you’re ready to assemble.
Preheat the oven to 180°C (360°F). Loosely wrap the peeled garlic cloves in aluminium foil. Put the shallots in a roasting tin, drizzle with 20 g (3⁄4 oz/1 tablespoon) of the olive oil and toss to coat, then sprinkle with the nigella and celery seeds. Add the foil bag with the garlic to the tin and roast for 20 minutes, or until the shallots have a bit of colour and are softened slightly. Set aside to cool.
Increase the oven to 190°C (375°F). Peel the beetroot and cut the larger ones into halves or quarters and leave the baby ones whole. Put in a separate roasting tin, drizzle with the remaining 60 g (2 oz) olive oil and cover the tin with foil. Roast for 30–40 minutes until tender. Set aside to cool.
To assemble the tarte, cut a disc of baking paper the same size as the base of your tatin pan and line the pan.
Combine the sugar, pomegranate molasses, vinegar and water in a small saucepan over a medium heat. Cook, stirring, until the sugar dissolves, then bring to the boil for a few minutes until the mixture becomes quite syrupy – just before it starts to caramelise. Remove the pan from the heat when you see lots of medium-sized bubbles on top.
Pour the caramel into the prepared pan and spread it evenly over the base. Set aside to cool for a few minutes. Lay the thyme sprigs over the caramel in the pan and arrange the beetroot, cut side up, on top. Squeeze the shallots and garlic in between the beetroot so that everything is snug, then sprinkle over the chopped herbs.
Lay the pastry sheet over the top, tucking the edges in between the vegetables and the side of the pan. Lightly brush the top of the pastry with egg wash and use a knife to make a couple of steam holes in the top. Refrigerate for 30 minutes to set the pastry, or until ready to bake.
Preheat the oven to 190°C (375°F). Bake the tarte tatin for 25 minutes, then reduce the oven to 180°C (360°F) and turn the pan. Bake for a further 15 minutes, or until the pastry is deep golden and puffed and flaky on top.
Rest for 10 minutes before inverting it onto your serving dish and removing the paper disc. Be careful not to burn yourself on the caramel! Season to taste with salt and pepper. Serve with a green salad and some goat’s curd or cheese.
If you do not have access to pomegranate molasses, substitute with balsamic vinegar.
The Taste Edit - Beetroot and Shallot Tarte Tatin https://thetasteedit.com/beetroot-and-shallot-tarte-tatin/