Tarte tatin is a traditional French dessert - an apple pie baked upside down - but it lends itself well to a savoury filling too. I saw a recipe recently by Yotam Ottolenghi for a potato version. That's a bit too carb-laden for me but other root vegetables work nicely, partly because they have an inherent sweetness.
Like the traditional apple tarte, you need to add a little sugar in some form or other to generate a caramel that will help hold all the filling together.
What you need:
2 medium cooked beetroot
Half a bag of fresh spinach
2 tsp demerara sugar
Half a pack of puff pastry
What to do:
Heat the oven to 220C. First steam the spinach, until it's slightly beyond wilted, set aside to cool then squeeze out as much water as you can. Cut the beetroot into 5mm slices. Melt a generous knob of butter in a medium-sized (20cm) ovenproof frying pan then sprinkle the sugar in. When the sugar has dissolved and the butter has started to sizzle, add the beetroot slices and gently fry them off on both sides (they should fill the pan in one layer). Scatter the spinach across the beetroot and season.
Roll out the pastry into a round just bigger than the pan. Take the pan off the heat and press the pastry over the beetroot and spinach, tucking the edges under. Pop it in the oven and bake for about 30 minutes until the pastry has risen up and is golden.
Take it out, let it cool a little and the, using oven gloves, place a plate bigger than the pan over it and quickly flip it over. The tarte should slip out intact onto the plate.
Those vacuum packs of cooked beetroots that you find in the supermarkets are perfect for this if you don't want to boil or roast then peel the beetroot from scratch, plus they are vinegar-free and cheap. If you don't like beetroot, you can make this with rounds of carrots or long slices of parsnip - scatter a few fresh thyme leaves over them at the frying stage.
If you don't have an ovenproof frying pan, start the cooking in your usual frying pan then transfer the beetroot to a cake tin and finish the prepping in that.
When I buy packs of puff pastry, I usually cut them in half or even quarters and freeze what I'm not using. Half a pack is about right for this (a quarter pack makes a puff pizza pie).
A whole tatin on its own is quite a filling meal. I like a generous slice on the side of a roast or some pulled pork or pulled beef, then I'll finish it for lunch next day.