To begin, preheat your oven to 175°C and lightly grease a 20cm square baking dish or similar sized round tin. In a bowl, whisk together the flour, baking powder and salt. Set this dry mix aside as your structural base.

Using a handheld mixer or wooden spoon, beat the softened butter with sugar in a large bowl until light and pale. This should take about 2 to 3 minutes. Scrape the bowl as needed to ensure an even texture.

Crack in the egg and pour in the vanilla extract. Beat until fully incorporated. The mixture might look slightly curdled at this point, but it will smooth out once the flour is added in stages.

Add half of the flour mix to the butter mixture, stirring gently. Follow with the milk, then the remaining flour. Mix only until just combined, overworking here can lead to a dense crumb.

Using a spatula, gently fold the blueberries through the batter. Take care not to crush them, especially if using fresh berries. Once mixed, spread the batter evenly into your prepared baking tin.

In a small bowl, combine the flour, brown sugar and cinnamon. Add the cold cubes of butter and rub with your fingertips until the mixture resembles coarse crumbs. Don’t overwork; the texture should stay lumpy.

Sprinkle the prepared crumb mixture evenly over the cake batter. Ensure some of the topping sits across the edges for variation in texture once baked.

Place the tin in the centre of the oven and bake for 35 to 40 minutes. The topping should be golden and the centre firm with a slight spring when gently touched. A skewer should come out mostly clean.

Allow the buckle to cool in the tin for 15 minutes before slicing. The crumb sets more as it rests, making for cleaner cuts and a better crumb.

Serve warm or at room temperature, with a dollop of whipped cream or spoon of yoghurt. It pairs beautifully with milky tea or strong coffee and makes an unpretentious but elegant dessert.