Upside-Down Plum Cake with Brown Butter and Cardamom
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By late August the plum tree gives up all at once — branches bowing, wasps working the windfalls, and a bowl of fruit on the counter that will turn from firm to collapsing in three days. This cake catches them at exactly the right moment: halved plums baked into a dark butterscotch caramel, under a crumb made with browned butter and freshly crushed cardamom. It slices warm, and the fruit keeps its shape and its tartness against the sweet base.
1 lb 2 oz (500 g) firm-ripe plums, about 8–10 small or 6 large
1 cup minus 1 tbsp (200 g) unsalted butter, divided
⅓ cup firmly packed (75 g) light brown sugar
1 tbsp (15 ml) lemon juice
¾ cup (150 g) caster or granulated sugar
3 large eggs, at room temperature
1 cup (130 g) plain (all-purpose) flour
½ cup (50 g) ground almonds, or fine polenta/cornmeal
1½ tsp baking powder
10 green cardamom pods (about 1 tsp seeds)
5 tbsp (75 g) full-fat plain yogurt or sour cream
Finely grated zest of 1 lemon, plus ½ tsp fine salt and a pinch of flaky salt
The Recipe
Line the base of a 9-inch (23 cm) round cake tin with baking paper and butter the sides. Use a solid tin, never a springform — the caramel is thin enough to seep through the seam and burn on the oven floor. Heat the oven to 350°F (180°C), fan 325°F (160°C).
Brown 170 g of the butter in a light-coloured pan over medium heat. It will foam, quieten, then start to crackle as the water boils off; keep swirling until the milk solids at the bottom turn the colour of hazelnut skins and the smell shifts from dairy to toasted nuts, 5–7 minutes. Scrape every brown speck into a bowl — that sediment is the flavour — and leave it to cool until it thickens to the consistency of soft mayonnaise. Do not skip this cooling: hot butter cannot hold air, and the cake will bake dense and greasy.
While it cools, halve the plums along their natural seam and twist to release the stones. Leave them as halves, not slices — the intact skin acts as a cup and stops the fruit collapsing into the batter. If a stone clings, cut around it rather than mashing the flesh.
Make the caramel base: melt the remaining 30 g butter with the brown sugar and lemon juice in a small pan over medium heat, stirring until it bubbles into a glossy, pourable sauce, about 2 minutes. The lemon juice keeps the sugar from crystallising into grit. Pour it over the lined tin base and tilt to cover, then scatter over a pinch of flaky salt. Arrange the plum halves cut side down, packed tightly in concentric circles — they shrink by roughly a quarter, and gaps now become bald patches later.
Crack the cardamom pods with the flat of a knife, discard the papery husks, and grind the black seeds to a coarse powder in a mortar. Pre-ground cardamom loses its eucalyptus-citrus top notes within weeks of milling; crushed fresh, it perfumes the whole kitchen and stands up to the caramel.
Beat the cooled brown butter with the caster sugar for 4–5 minutes until noticeably paler and fluffy — you are forcing in the air bubbles that make this cake tender. Add the eggs one at a time, beating well and adding a tablespoon of the flour with the second and third; the flour binds the liquid and stops the mixture curdling into a grainy split.
Whisk the remaining flour with the ground almonds, baking powder, ground cardamom, lemon zest and fine salt, then fold into the batter in two additions, alternating with the yogurt. Stop the moment no dry streaks remain — the batter should drop thickly from the spoon and hold a ribbon for a second or two. Overmixing develops gluten and gives a rubbery crumb.
Spoon the batter in blobs over the plums, then spread gently from the centre outwards with the back of the spoon so you don’t drag the fruit out of position. Bake 45–55 minutes: the cake is ready when the edges have pulled slightly away from the tin, the top springs back without leaving a dent, and a skewer into the centre (avoiding fruit) comes out with a few moist crumbs, not wet batter. Juices bubbling up the sides are a good sign.
Rest exactly 10 minutes, then run a knife around the edge, set a serving plate over the tin and invert in one confident movement. Ten minutes lets the caramel thicken enough to cling to the fruit; leave it much longer and the sugar sets like glue and tears the top off the cake. Lift the tin, peel the paper, and replace any plum that stayed behind.
