WHAT YOU NEED

500g (1lb 2oz) waxy potatoes, peeled
1 large bunch rainbow chard or silverbeet (Swiss chard)
2 Tbsp olive oil
1 brown onion, finely chopped
3 garlic cloves, finely chopped
1 Tbsp thyme leaves
½ tsp ground cumin
½ tsp smoked paprika
200g (7oz) crème fraiche
2 Tbsp dijon mustard
3 eggs
1 cup (100g) grated gruyere or other mild, nutty cheese
½ cup (50g) finely grated parmesan cheese
2 Tbsp sesame seeds (optional)
2 Tbsp nigella seeds (optional)
Tomato chutney, to serve

Sour cream pastry
⅔ cup (160g) sour cream
2 cups (300g) plain (all-purpose) flour, plus extra for dusting
1 cup (250g) chilled unsalted butter, cut into cubes
½ tsp sea salt

For the pastry, blitz the sour cream, flour, butter, and salt in a food processor for a few seconds or until just combined. Turn the pastry out onto a work surface and gently bring it together into a disc. Wrap the pastry and pop it in the fridge to chill for 30 minutes.

Add the potatoes to a saucepan of water, bring to the boil and cook until tender when pierced with a knife. Drain and set aside to cool.

Pull the chard leaves away from the stalks (reserve the stalks to make a chard stalk pickle). Tear the leaves into smallish pieces.

Heat the oil in a large saucepan over medium heat. Cook the onion for 10 minutes or until softened. Add the garlic, thyme, cumin, and paprika and cook for a few minutes. Add the chard leaves and toss everything around for a few minutes so the chard cooks down and softens. Remove from the heat and set aside to cool.

Preheat the oven to 200°C (400°F). Line a large baking tray with baking paper.

Combine the crème fraîche, mustard, and two of the eggs in a bowl. Season with salt and pepper, add the cheeses and whisk to combine. Stir in the chard mixture.

Cut the pastry disc in half. On a lightly floured surface, roll out one half into a flat round that’s about 5 mm (¼ inch) thick. Repeat with the second piece of pastry. Place one pastry round on the baking tray. Thinly slice the cooled potatoes and arrange them in a circle on the pastry, leaving a 4 cm (1½ inch) border. Carefully pour the onion and chard mixture over the potato. Place the second pastry round on top and crimp the edges to seal. Whisk the remaining egg and brush it over the pastry. Sprinkle the sesame and nigella seeds over the top, if using.

Bake the pie for 30–35 minutes or until puffed and golden. Cut it into wedges and serve with tomato chutney and chard stalk pickle.