1 1/2 cups (225g) plain flour
125g chilled unsalted butter, chopped (see note)
1/3 cup (80g) sour cream
1 large egg, at room temperature
20 small-to-medium sage leaves
40g unsalted butter
1 large leek, thinly sliced into rounds
11 large eggs, at room temperature
1/2 cup (120g) sour cream
2/3 cup (80g) coarsely grated aged cheddar
10 (250g total) rashers streaky bacon
Small sage leaves (optional), to decorate
Extra virgin olive oil, to drizzle
To make the pastry, place flour, 1/4 tsp fine salt and chilled butter in a food processor. Pulse until mixture resembles coarse breadcrumbs. Add sour cream and egg. Pulse until pastry comes together, adding 1-2 tsp cold water if needed. Use your hands to form pastry into 2 even-sized balls, then roll out each ball between 2 sheets of baking paper into a 25cm round.
Press sage leaves gently onto the surface of one of the pastry rounds. Place the other pastry round on top. Use a rolling pin to roll gently to enclose the leaves between the pastry rounds, then roll out to a 30cm round. Wrap in plastic wrap and chill for 1-2 hours or until slightly firm but still pliable.
Preheat oven to 200°C/180°C fan-forced. Grease base and side of a 20cm-round, 7cm-deep springform pan, then line the base with baking paper. Remove sage pastry round from the fridge and roll out further to a rough 35cm round. Use your rolling pin to help transfer the pastry into the prepared pan. Using your fingers, press pastry snugly into the base and up the side. Trim overhanging pastry to leave a 1cm-high pastry collar above the pan’s rim (by doing this, when you release the side of the pan after baking, the pastry edge won’t snap off).
Line pastry shell with baking paper and fill with baking beads. Bake for 30 minutes. Remove baking paper and beads, prick the pastry base a few times with a fork, then bake for a further 15-20 minutes or until pastry is cooked and golden brown all over. Transfer to a wire rack to cool. Meanwhile, for the filling, place the butter and leek in a frypan over low heat. Cook, stirring often, for 8-10 minutes or until leek is soft and translucent. Set aside in pan to cool to room temperature. Reduce oven to 180°C/160°C fan-forced.
When pastry has cooled, whisk 4 of the eggs and the sour cream in a bowl until smooth. Stir in cooled leeks, cheddar, a good grind of black pepper and 1/2 tsp salt flakes. Line the side of cooled pastry shell with 3 rashers of the bacon before pouring in egg and leek mixture. Coil each of the remaining 7 bacon rashers to form rings. Nestle 6 into the egg mixture around the outside edge of the pastry shell. Place remaining ring in the centre of the pie. Crack the 7 remaining eggs into each ring, being careful to keep the yolks whole. Scatter a few small sage leaves on top, if desired, then drizzle with oil.
Place a large baking tray on a lower shelf in the oven (to catch any butter from the pastry that releases on baking). Bake the pie on middle shelf of oven for 1 hour 10 minutes-1 hour 15 minutes or until pie filling is just set (cover the pie loosely with foil if the pastry starts to get too brown). Cool pan on a wire rack for at least 45 minutes before slicing and serving warm, or cool to room temperature to serve.