Name: Rustic Plum Upside Down Cake
Prep time: 20 min
Cook time: 35 min
Total time: 55 min
Ingredients: 1 lb (500 g) firm plums, pitted and cut into 1/2-inch slices; 3 tbsp (45 g) unsalted butter; 1/2 cup (100 g) granulated sugar; 2 tbsp (30 ml) water; 1/3 cup (75 g) softened butter; 1/3 cup (70 g) granulated sugar; 3 tbsp (45 g) sour cream; 1 tsp vanilla extract; 1 1/4 cup (160 g) all-purpose flour; 2 tsp baking powder; 1/4 tsp salt; 1 tsp ground cinnamon (optional)

The kitchen counter was covered in sticky red juice yesterday afternoon after I sliced into a fresh batch of fruit that refused to cooperate. I usually lean on a trusty cast iron skillet when I bake this plum upside down cake because it holds an even heat and keeps the edges from scorching.

It is the kind of simple weekend project that makes the whole house smell like warm cinnamon and burnt sugar before anyone even wanders in to ask what is ready.

Prep: 20 minutes · Cook: 35 minutes · Total: about 1 hour and 15 minutes · Serves: 6

How do you keep a plum upside down cake from sticking to the pan? You need to flip the cake while it is still warm so the caramel layer releases cleanly.

If you let it cool completely in the skillet, the sugar hardens like glass and locks the fruit to the bottom.

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Ingredients for Plum Upside Down Cake

1 lb (500 g) firm plums, pitted and cut into 1/2-inch slices
3 tbsp (45 g) unsalted butter
1/2 cup (100 g) granulated sugar
2 tbsp (30 ml) water
1/3 cup (75 g) softened butter
1/3 cup (70 g) granulated sugar
3 tbsp (45 g) sour cream
1 tsp vanilla extract
1 1/4 cup (160 g) all-purpose flour
2 tsp baking powder
1/4 tsp salt
1 tsp ground cinnamon (optional)

Ingredient Notes

You want to look for firm fruit that holds its shape through a long bake, as soft or overripe ones turn to mush in the oven. I always use full-fat sour cream because it gives the crumb a rich texture that lightens up nicely with the baking powder.

If you skip the cinnamon, the pure caramel flavor shines right through, but a heavy pinch adds a nice warmth that fits a lazy Sunday afternoon.

How I Make It

Melt the caramel. Combine the 3 tablespoons of butter, 1/2 cup of sugar, and water in your skillet over medium heat until the mixture bubbles and turns a deep golden brown, about 5 minutes.
Arrange the fruit. Remove the skillet from the heat and carefully press the firm plum slices into the hot caramel in a tight concentric circle with the cut sides facing down.
Mix the batter. Whisk the softened butter and 1/3 cup of sugar in a bowl until smooth, then stir in the sour cream and vanilla extract until combined.
Add dry ingredients. Fold the flour, baking powder, salt, and cinnamon into the wet mixture gently until a thick batter forms without any dry streaks left behind.
Spread the batter. Spoon dollops of the thick batter evenly over the layered fruit in the skillet, then use a spatula to smooth it out toward the edges without disturbing the plums underneath.
Bake the cake. Place the skillet in a 350°F oven and bake it until the top springs back to a light touch and the edges pull away slightly from the sides, about 35 minutes.
Flip the cake. Invert a large plate over the skillet while the pan is still warm to the touch, and carefully flip it over in one swift motion to release the fruit.

Make-Ahead and Leftovers

You can keep leftovers covered at room temperature on the counter for up to two days, though it rarely lasts that long in my house. If you want to keep it longer, wrap individual slices tightly in plastic wrap and store them in the fridge for up to four days.

Bring it back to room temperature before eating, or pop a slice in the microwave for ten seconds to soften the caramel back up.

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