Gluten-Free Plum Cake (Zwetschgenkuchen)

Late summer into autumn is Zwetschgen season — the small, deep-purple Italian prune plums that hold their shape when baked and turn jammy and intense in the oven. Germany’s answer to a glut of them is Zwetschgenkuchen, and it takes to gluten-free baking beautifully, because the plums do the heavy lifting and the sponge underneath only has to be tender and buttery. Ground almonds keep that sponge moist and give it the structure gluten-free cakes often lack — so this is a forgiving one to start with.

Makes one 20 cm (8 inch) round cake, about 8 slices. Hands-on 20 minutes; baking around 45 minutes.

Ingredients

For the sponge base

• 150 g soft unsalted butter, plus a little for the tin
• 120 g caster sugar
• 3 medium eggs, at room temperature
• 120 g certified gluten-free plain flour blend
• 80 g ground almonds
• 1½ tsp gluten-free baking powder
• ½ tsp xanthan gum (skip if your flour blend already contains it)
• Zest of ½ lemon
• 1 tsp vanilla extract
• Pinch of salt

For the top

• 500–600 g Zwetschgen (prune plums) — about 12–16, halved and stoned (quartered if large)
• 1 tbsp caster sugar mixed with ½ tsp ground cinnamon
• Optional: 20 g flaked almonds

Method

1. Heat the oven to 180°C conventional / 160°C fan / gas 4. Butter a 20 cm springform tin and line the base with baking paper.
2. Prepare the plums. Halve and stone them. Cutting a small cross into the cut side, or scoring the skin, helps them open and release juice as they bake. Set aside.
3. Cream the butter and sugar for 3–4 minutes until pale and fluffy — this is where the lightness comes from, so don’t rush it.
4. Add the eggs one at a time, beating well after each. If it looks curdled, add a spoonful of the flour.
5. Fold in the dry ingredients — gluten-free flour, ground almonds, baking powder, xanthan (if using), salt, lemon zest and vanilla — until just combined. The batter is thick; that’s correct.
6. Spread the batter into the tin and level it. Arrange the plums on top, cut side up, packed closely — they shrink as they bake, so crowd them. Press them lightly into the batter.
7. Scatter the cinnamon sugar over the plums, and the flaked almonds if using.
8. Bake for 40–50 minutes. It’s done when the sponge is golden, springs back to a light touch at the edge, and a skewer pushed into the sponge (not a plum) comes out clean. The plums will be soft and glistening. If the top colours too fast, loosen a piece of foil over it for the last 10 minutes.
9. Cool in the tin for 15 minutes, then release the ring and cool on a rack. Gluten-free sponges firm up as they cool, so resist cutting it hot.

Tips and swaps

• Plums: true Zwetschgen are firmer and less watery than round dessert plums, which is why they hold up. If you can only get round plums, use slightly fewer and expect a wetter, jammier result — still lovely, just bake a few minutes longer.
• Dairy-free: a good block-style plant butter works in place of the butter.
• Nut-free: replace the ground almonds with an extra 80 g of your gluten-free flour blend plus 1 tbsp of milk to keep it moist — the crumb will be a little less tender but still good.
• Serve just warm or at room temperature, dusted with icing sugar, with a spoon of whipped cream. In Germany it’s afternoon Kaffee und Kuchen; it’s also a very good pudding.

A note on the flour

Use a certified gluten-free flour blend and certified ground almonds — naturally gluten-free ingredients are still milled on shared equipment, so certification is what makes them reliable for coeliac baking. The ground almonds here aren’t just for flavour: they add moisture and help the crumb hold together, a trick worth borrowing for other gluten-free sponges. If you want to understand why a blend behaves the way it does, our guide to gluten-free flours explains who does what in the bowl.