Method

• 1.
  For the ricotta (see recipe notes), place the milk and cream in a large heavy-based saucepan over medium-low heat. Using a cooking thermometer, slowly bring to 60°C, then gently stir in the vinegar. Continue to heat slowly to 85°C. Turn off the heat and allow to sit for 15 minutes. Using a perforated spoon, scoop the cheese from the whey and transfer to a cheese cloth or fine sieve set over a bowl until completely cooled. Set aside until ready to use.
• 2.
  Preheat the oven to 140°C/120°C fan-forced. To make the dried bread flour, place the sourdough pieces on a baking tray and dry in the oven for 40-45 minutes, until completely dry, toasted and crisp but with no colour. Remove from the oven and cool completely, then transfer to a food processor and whiz until a fine powder.
• 3.
  To make the pastry, place the flour, 1/4 tsp fine salt and sugar in a large bowl. Add the butter to the flour and, using your fingertips, rub the butter into the flour until the flour resembles a rough crumb. Add the breadcrumbs and mix until just combined. Add the egg and milk and bring together to form a dough, making sure not to overmix. Shape into a flat disc, wrap in plastic wrap and place in the fridge to rest for at least 30 minutes.
• 4.
  Increase oven temperature to 180°C/160°C fan-forced. On a well-floured work surface, flatten the pastry then roll out to a 4-5mm thick, 35cm disc. Grease a 23cm x 3.5cm, loose base fluted tart pan and line with the pastry, pressing the base and side to secure the pastry. Trim the edges and prick the bottom of the tart with a fork. Place in the freezer to rest for 30 minutes.
• 5.
  Place a piece of baking paper on top of the pastry and fill with baking beads or dried beans. Blind bake for 15-18 minutes, then remove the beads and baking paper and return to the oven for a further 15-18 minutes, until the pastry is light golden and dry to touch.
• 6.
  Meanwhile, for the tart filling, heat a large deep frypan with the butter and oil over high heat. Add the leek and silverbeet stems. Season to taste and cook, stirring occasionally, for 2-3 minutes, until the stems begin to soften. Add the leaves and cook for a further 6-8 minutes, until leaves are wilted and stems and leeks are tender. Season to taste. Transfer to a heatproof bowl and cool completely.
• 7.
  Stir in the herbs with the spices, zest and three-quarters of the fresh ricotta. Stir in the eggs (use as little egg as possible, but be sure the whole mixture is coated). Add a third egg if needed. Transfer the filling to the tart base and smooth the surface. Top with remaining ricotta. Bake for 15-20 minutes, until the filling is set. Remove from the oven and allow the tart to cool for 5 minutes before serving.