Food for the (Gluten Intolerant) Soul

This tart sits somewhere between a crumble and a shortcrust pie, and that is exactly what makes it work. A buttery, biscuit-like dough forms the base and the topping, with a jammy, slow-cooked berry filling in between. It comes together without any specialist equipment and handles gluten-free flour just as well as plain.
It is the kind of thing you make on a Sunday and eat all week.

A note on the berries
Frozen summer berries are ideal here. They are consistent, affordable year-round, and release enough liquid when defrosted to give the filling real depth once cooked down. The key is patience with straining. Do it twice: once before cooking, once after. Skipping this step is the most common reason a tart like this ends up with a soggy base, and it is entirely avoidable.
The sugar quantity in the filling is deliberately a range. Taste the fruit once it has cooked and adjust. Berries vary considerably in sweetness depending on the batch.

Ingredients
For the dough:
420g plain flour or gluten-free flour
2.5 tsp baking powder
100g caster sugar
150g butter, at room temperature
1 large egg
3 tbsp milk or orange juice
For the filling:
1kg frozen summer berries, defrosted and strained
50 to 100g sugar, to taste
4 tbsp smooth jam, plus a little extra for the base

Method
Start with the filling, as it needs time to cool before you assemble the tart.
Strain the defrosted berries through a sieve and discard the liquid. Tip the berries into a saucepan with the sugar and cook over a low heat for around 20 minutes, stirring occasionally. Stir in the jam at the end. The mixture should be thick and glossy, not watery. Set aside and leave to cool completely.
When you are ready to bake, preheat the oven to 160°C (gas mark 3).
For the dough, beat the butter and sugar together until just combined. Add the egg and milk or orange juice, then mix again. Add the flour and baking powder and bring together into a soft dough. Stop as soon as it is uniform; overworking it will tighten the texture.
Press two thirds of the dough into the base and up the sides of a tart or pie tin, aiming for roughly 2cm up the sides. Spread a thin layer of jam over the base. Strain the cooled berry mixture one final time, then spoon it over the jam and spread evenly.
Crumble the remaining dough over the top in rough, uneven pieces. Do not worry about coverage; the gaps are part of it.
Bake for approximately one hour, until the top is golden and you can see the filling bubbling at the edges.
Leave to cool in the tin before slicing. It holds its shape better cold, but it is most enjoyable slightly warm, with cream or nothing at all.

Serves 8. Keeps well for three days at room temperature, longer in the fridge.