To make the tart mix, in a bowl add the beetroot, ricotta, egg, chives, nigella seeds and half the Parmesan and mix together. Season with salt and pepper.
Butter 4 ramequins and set aside for later.
Flatten the filo sheets and brush each one with melted butter. Fold over itself so it’s half the size, then brush with butter again. Rustically put each one into a ramequin, pushing down so it’s touching the bottom.
Divide the mix between each case.
Sprinkle the rest of the Parmesan over each one and put in the oven for 10-12 minutes.
When ready, drizzle with olive oil and either serve in the pots or lift out so it’s released from the pot.