Blueberry and Lemon Thyme Cornmeal Buckle with Almond Streusel
0
A blueberry bush in a tub of acidic compost ripens in waves rather than all at once, and the berries only turn sweet five to seven days *after* they turn blue — ripe ones drop into your palm when you roll them with a thumb. That slow trickle suits a buckle: a single-layer cake that buckles under the weight of the fruit. Cornmeal keeps the crumb standing, lemon thyme from the same doorstep pot perfumes the sugar.
2½ cups (350 g) blueberries, or bilberries, haskap or blackcurrants
1 tbsp lemon thyme leaves, stripped from the stems (about 8 sprigs)
¾ cup (150 g) caster sugar
½ cup (115 g) unsalted butter, soft enough to dent easily
2 large eggs, at room temperature
1 cup (130 g) plain flour, plus 1 tbsp for the berries
⅓ cup (55 g) fine cornmeal or fine polenta (not instant)
1½ tsp baking powder
½ tsp fine sea salt
½ cup (120 ml) whole-milk plain yogurt or buttermilk
finely grated zest of 1 unwaxed lemon
For the streusel: ⅓ cup (45 g) plain flour, ¼ cup (50 g) light brown sugar, ⅓ cup (30 g) flaked almonds, 3 tbsp (45 g) cold butter, cubed
The Recipe
Stir the cornmeal into the yogurt and leave it on the counter while you work, at least 20 minutes. The grains swell and soften; skipped, they stay sandy on the tongue no matter how long the cake bakes. Do not skip this step.
Tip the caster sugar into a bowl with the lemon thyme leaves and lemon zest and rub everything together with your fingertips for 30 seconds, until the sugar smells sharply of citrus and lemon oil and looks faintly green. The sugar crystals act as an abrasive, tearing open the oil glands in the leaf — infusing thyme into liquid gives a medicinal note instead of this bright one.
Make the streusel: rub the cold butter into the flour, brown sugar and almonds with your fingertips until you have clumps between pea and hazelnut size, then freeze it on a plate for 15 minutes. Cold fat holds its shape long enough to crisp; warm streusel simply melts down into the batter and disappears.
Beat the soft butter with the thyme sugar for 4–5 minutes, until the mixture pales to ivory and visibly increases in volume, scraping the bowl twice. This whipped air is most of your lift. Add the eggs one at a time, beating 30 seconds after each — the batter should look like thick mayonnaise. If it looks curdled, add a spoonful of the flour to bring it back together.
Whisk the plain flour, baking powder and salt together, then fold them into the batter in three additions, alternating with the cornmeal-yogurt mixture, stopping the moment the last floury streak vanishes. The batter should fall from the spatula in a heavy ribbon. Beating past this point builds gluten and gives a rubbery, tunnelled crumb.
Toss the blueberries with the reserved tablespoon of flour until dry and dusty-looking, then fold two-thirds through the batter with four or five strokes and scatter the rest over the surface. The flour coat thickens the juices as they burst, so the fruit stays suspended instead of sinking into a wet seam at the base.
Spread the batter into a lined 8-inch (20 cm) round tin, levelling it and hollowing the centre by about 1 cm with the back of a spoon so the cake rises flat rather than domed. Scatter the frozen streusel over the top in an even layer, right to the edges.
Bake at 350°F (180°C) for 45–55 minutes, turning the tin once at the 30-minute mark for even colour. It is ready when the streusel is deep gold, the berries have burst into dark purple pools that bubble slowly at the edges, and a skewer pushed into the centre comes out with moist crumbs but no wet batter. The centre should spring back when pressed.
Cool in the tin for at least 20 minutes before cutting. The starch is still setting and the berry juice is near boiling; slice it straight from the oven and the crumb collapses around the fruit. Serve warm with crème fraîche, cold pouring cream or a spoonful of thick yogurt.
