Plum, raspberry jam & cardamom crumble squares

Add a layer of jam to bakes like these bars for a simple way to get more flavour. These moreish crumble squares are made with raspberry jam and plums

4 cardamom pods, seeds crushed
1 tbsp lemon juice (reserve the lemon, see below)
250g low-sugar, high-fruit raspberry jam
10 slightly unripe plums, halved and stoned (you may need more, depending on size)
125g cold butter, cut into chunks, plus extra for the tin
150g ground almonds
150g plain flour
115g caster sugar
½ lemon, zested
½ tsp vanilla extract
50g plain flour
35g ground almonds
45g cold butter, cut into small chunks
50g light brown soft sugar
½ lemon, zested
25g flaked almonds
icing sugar, for dusting (optional)

Butter and line a 30 x 20cm baking tin with baking parchment, leaving an overhang so you can lift out the traybake later, then butter the parchment. Heat the oven to 180C/160C fan/gas 4.
To make the pastry, put all the ingredients, except the vanilla, into a food processor and blitz until the mixture resembles breadcrumbs. Add a couple of teaspoons of very cold water and the vanilla, then blitz again. The mixture should come together into a ball. If it doesn’t, add a little more cold water and blitz again. Press into the tin using your fingers and the back of a large spoon, then bake in the oven for 15-18 mins until pale golden. Leave to cool for 15 mins.
Stir the cardamom seeds and the lemon juice into the jam until smooth. Spread the jam over the pastry base, leaving a 2cm border all the way round. Cut each plum half into 1cm slices. Lay these in rows, overlapping, on top of the jam.
To make the crumble, put the flour, ground almonds, butter, sugar and lemon zest into a food processor (you don’t need to wash it out first), and blitz until the mixture looks like breadcrumbs. Tip this over the plums and scatter the flaked almonds on top. Bake for about 35-40 mins until the top is golden and the plums are tender. Leave to cool completely in the tin.
Carefully lift the traybake out of the tin onto your work surface using the baking parchment. Leave for a few hours so the fruit can settle. Cut into squares or rectangles, then sift some icing sugar over the top, if you like.