Preheat the oven to 375F.

Prepare the pastry by mixing the sugar, almond and all-purpose flour together. Add the butter with your hands until the mixture resembles breadcrumbs. Beat the egg yolk and add it into the mixture, working the dough together, kneading it with your hands until it binds together smoothly. Wrap and refrigerate the dough for 30 minutes or until firm. This can be done in advance. Allow the dough to rest for 10 minutes at room temperature and then roll the dough to fit a 9-inch tart shell. The dough is soft and can crumble, but holes can be easily patched with extra pieces of dough. Once you have the dough nicely in the tart shell, prick a few times with a fork, cover with parchment and fill with pie weights or beans to blind bake. Bake for 15 minutes, then remove the paper and weights and bake for another five minutes.

While the pastry is baking, prepare the crumb topping. Rub the sugar, salt, butter and flour together until it resembles breadcrumbs. Set aside.

Prepare the custard by whisking together the egg, cream and sugar. Add the pinch of cinnamon and the almond extract and set aside.

Remove the tart shell from the oven and allow to cool slightly. Reduce the oven temperature to 350F. Fill the shell with the blueberries, then pour the custard mixture evenly over the berries, allowing it to settle to the bottom of the tart. Top the berries with the crumble mixture.

Bake for 30 to 40 minutes, until the edge of the tart is golden brown and the berries are juicy and bubbly. Remove the tart from the oven to cool before serving with softly whipped cream.