Preheat the oven to 170°C fan-forced.

Lightly grease a 20 × 30 cm slice tin, then line it with baking paper, leaving an overhang on the two long sides to help lift the slice out after baking.

In a large mixing bowl, whisk together the flour, caster sugar, baking powder and salt.

Add the cold, cubed butter. Using your fingertips, rub the butter into the flour mixture until it resembles coarse breadcrumbs with a few pea-sized pieces of butter remaining.

Add the egg yolk and vanilla extract directly to the bowl. Using a fork, mix until the egg is evenly distributed and the mixture begins to form large clumps.

Using your hands, gently squeeze and press the mixture together until it forms a soft dough. Do not knead.

If the dough still feels dry and crumbly, add 1 teaspoon of cold water at a time, gently working it through the dough after each addition until it just comes together.

Transfer the dough to the prepared tin.

Using your fingertips, press the dough evenly over the base, making sure it reaches right into the corners.

Use the flat base of a drinking glass or measuring cup to firmly compact and smooth the surface.

Place the tin onto the middle oven shelf and bake for 15 minutes, or until the edges are just beginning to turn lightly golden while the centre remains pale.

Remove from the oven and allow the base to cool for 5 minutes.

Place the raspberry jam into a microwave-safe bowl and warm for 15–20 seconds, or gently warm it in a small saucepan until spreadable.

Using the back of a spoon or a small offset spatula, spread the jam evenly over the warm base, taking it right to the edges in a thin, even layer.

In a large mixing bowl, combine the desiccated coconut, caster sugar and salt.

Add the melted butter, egg, vanilla extract and milk.

Using a wooden spoon, mix until everything is evenly combined. The mixture should be soft, moist and slightly sticky, holding together when pressed gently with the back of the spoon.

Using two teaspoons, drop small spoonfuls of the coconut mixture evenly over the jam.

Once all the topping has been added, gently spread it with the back of a spoon until the jam is completely covered.

Take care not to drag the jam through the coconut mixture.

Lightly smooth the surface without pressing down firmly.

Return the slice to the oven and bake for 20–22 minutes, or until the coconut is lightly golden and the centre no longer looks wet.

The topping should still feel slightly soft when gently pressed, as it will continue to firm as it cools.

Leave the slice to cool completely in the tin.

Using the baking paper overhang, carefully lift the slice from the tin and place it onto a chopping board.

Using a large sharp knife, cut into 16 squares, wiping the blade clean between each cut.