Nine years after opening her cult bakery in North Melbourne, Natalie Paull published her recipes in a bake-your-own-adventure cookbook in March. Inside Beatrix Bakes you’ll find these rhubarb custard crumble pies, or “crunch-squidge-crunch sandwiches” as Paull calls them.

“I adore the feeling of cradling one of these pies, still warm, the moment before eating,” she writes.

“The words below are beyond a recipe and into blueprint territory because you can make these with so many different fruits and spike the crumble with spices or nuts. Keep the custard a classic vanilla though, a safe and creamy canvas on which to create your fruit crumble masterpiece.”

The pies are filled with vanilla custard, sweet roasted rhubarb and ginger, and topped with a crunchy butter-oat streusel – “nubbly, buttery biscuity boulders”. They take around 30 minutes to assemble and bake once all four parts are ready. But if you’re starting from scratch, it takes around three hours from start to finish.

These are best eaten warm.

Rhubarb Custard Crumble Pies
Makes 8
Prep time: 3 hours
Bake time: 30 minutes

Super-flaky pie crust
240g plain flour
2g fine sea salt
190g unsalted butter (cold, diced)
40ml iced water
1 egg yolk

Roasted rhubarb with ginger (makes about 450g, including juice)
2 small bunches rhubarb
5cm piece of ginger
Juice of 1 orange (or mandarin, tangelo)
40g caster sugar

Vanilla pastry custard (makes about 400g)
250g full-fat milk
1 vanilla bean
3 egg yolks
15g plain flour
10g cornflour
65g caster sugar
25g unsalted butter, room temperature

Butter-oat streusel (makes about 450g)
100g old-fashioned or rolled oats
120g plain flour
100g light muscovado (or soft brown) sugar
150g unsalted butter, very soft and squidgy
2 tsp fine sea salt
1½ tsp freshly ground cinnamon

Method:
Super-flaky pie crust (20 minutes prep, 2 hours rest, 50 minutes blind baking)
Put the flour and salt in a wide mixing bowl. Rub the butter into the dry ingredients just until the butter lumps are the size of whole almonds and the flour has just taken on a yellowy hue.

Combine the iced water and egg yolk and add to the buttery flour. Keep mixing with your hands until it looks like shaggy Play-Doh.

Loosely wrap the dough in plastic wrap, then press it into a 2cm-thick disc, squeezing around the edge to smooth out any cracks. If the dough is not too warm, you can start rolling now. If it feels sticky, chill in the fridge for at least 15 minutes.

Place the dough on a lightly floured surface and press it out with the palm of your hand. This helps to prevent large cracks. Give the dough one or two short, pressured rolls with the pin before lifting and moving the dough 90 degrees, making the rolls longer as the dough circle widens. Dust underneath the dough at regular intervals to prevent sticking.

Roll the dough into strips at least as wide as your pastry cutter, then cut out 8 10cm circles. Line snugly into the tins. Use your fingers to push off any overhang.

To blind bake, preheat the oven to 180°C. Cover the frozen dough with a piece of aluminium foil, tucking it into the edge of the tin. Bake for 30–40 minutes until the crust is an even biscuity brown colour.

Roasted rhubarb with ginger (30 minutes prep)
Preheat the oven to 160°C. Remove the rhubarb leaves (they're poisonous so trim them off completely), then cut the stems on a diagonal into 6cm batons. Slice in half lengthways if the pieces are very thick. Rinse in a colander. Peel and slice the ginger into four coin-like discs.

Put the rhubarb batons, ginger, juice and sugar in a generously sized non-reactive roasting tin. Massage the ingredients together.

Place a sheet of baking paper over the rhubarb and then cover tightly with foil. Roast for 10–30 minutes – the timing depending on the thickness of the stalks and the heaviness of your baking vessel. Do the first check at the 10-minute mark. Push a piece of the rhubarb near the centre; it should yield to the lightest poke but still be holding its shape.

Remove from the oven and leave to cool with the paper on top.

Vanilla pastry custard (30 minutes prep, plus chilling time)
Pour nearly all of the milk into a small saucepan but reserve 1 tablespoon to add to the yolk mix. Split and scrape the vanilla bean into the milk, then place the pan on the stovetop and scald the milk over a medium–high heat.

Just before the eager bubbling, whisk together the egg yolks, flours, sugar and reserved milk in a small heatproof bowl. The milk helps to bind the egg and flour mix. Don’t do this too far in advance or the mix will form small, hard yolky lumps.

Pour half the hot milk into the egg mix and whisk well, then pour in the remainder. Return the mix to the pan, place over a medium-high heat again, and whisk at a medium tempo until the mix thickens. Take extra care to whisk right into the corner of the pan – where the side meets the base. Speed up the mixing as the custard thickens – it will look lumpy but just whisk hard and it will all come together into a thick paste in 1 to 2 minutes. As soon as the custard comes to the boil, keep whisking for another 30 seconds.

Remove the pan from the heat and whisk in the butter. Remove the vanilla bean, scrape the custard into a plastic container and press a piece of plastic wrap on the surface of the custard to prevent a rubbery skin forming. Chill for an hour.

Butter-oat streusel (10 minutes mixing)
Whiz the oats in a food processor until super fine. Tip into a bowl and add the remaining ingredients. Rub and squeeze the butter in with your fingers until all the dry ingredients are coated in butter and the mix easily forms small buttery clumps when squeezed in your fist. Take care not to overmix everything to the point where you make an actual dough.

Assembly and baking
Preheat the oven to 180°C. Place the blind-baked crusts, still in the tins, on a heavy baking tray.

Drain the roasted rhubarb for a few minutes in a colander to remove the excess liquid. Spoon or pipe the vanilla pastry custard evenly among the crusts, then make a “nest” in the custard by pushing it with the back of a spoon. Strew pinches of the drained rhubarb over the top of the custard. (The pies can be built with rhubarb and custard at any temperature.)

Pile the butter-oat streusel on top, allowing a little fruit to be visible around the edge.

Bake for 20–30 minutes until the fruit starts to bubble at the sides and the crumble is toasty brown on top. The perfect eating temperature is after a 20-minute cool down.

Note: pies can be wrapped and chilled overnight and refreshed in a low oven the next day.

This is an edited extract from Beatrix Bakes by Natalie Paull, published by Hardie Grant Books. Buy it online or in bookshops.

beatrixbakes.com