This oven-baked plum jam does the work for you: 3 kg of ripe plums bake down slowly in the oven with just a little brown sugar, until they turn into a thick, glossy, spoonable jam. A splash of dark rum and a handful of toasted walnuts go in at the end. No pectin, barely any sugar, and it makes about 6+ jars.
I have a garden full of plum trees, so every autumn my family makes țuică (plum brandy) and jars of plum jam – it is simply what you do when the branches are bending under the fruit. This year I wanted something lighter than the cauldron jam we cook over a fire for hours, so I tested a version baked in the oven instead: far less sugar, no constant stirring, and the plums caramelize slowly on their own. The rum ties it all together, and the walnuts come from the same garden. The photos below are from my own orchard, in spring blossom and at harvest.
This Recipe Works If You Need
- A low-sugar jam that sets naturally, without pectin
- A hands-off way to use a big harvest of plums
- A vegan preserve with a grown-up rum-and-walnut flavor
- Homemade gifts in a jar
Why You’ll Love This Oven-Baked Plum Jam
- Baked, not babysat. The oven does the reducing, so no standing over a splattering pot.
- Less sugar. Just 300 g for 3 kg of plums
- Rum and walnuts. A splash of dark rum and toasted walnuts make it feel special.
- No pectin. Slow oven evaporation and the plums’ own pectin set it.
Ingredient Notes
Plums are the star. Ripe, sweet plums give the best flavor and the deepest color. Freestone varieties are easiest to pit, but any plum works.
Brown sugar is all it takes. Just 300 g keeps the jam barely sweet and lets the fruit shine; use white if that is what you have, or add more for a sweeter jam that keeps longer.
Rum gives that warm, festive aroma. Use a splash of dark rum or 2 vials of rum essence – most of the alcohol bakes off during the long, slow cook.
Walnuts are stirred in right at the end so they stay crunchy. Toast them first for the best flavor. A pinch of cinnamon is lovely too.
Tips and Variations
- Lower the heat near the end. Drop the temperature so the thickening jam does not burn.
- Make it smooth. Blend it for a magiun-style spread, or leave it rustic with pieces.
- Add the rum late. Stir it in near the end so the aroma stays bright.
- Toast the walnuts. A few minutes in a dry pan deepens their flavor.
Storage and Make Ahead
- Sealed jars: store in a cool, dark place.
- Opened jar: because this jam is low in sugar, keep it in the fridge and use within 3 to 4 weeks.
- Jars: always use clean, sterilized jars for the best shelf life.
For more fruity preserves and plum recipes, try my apricot jam in the slow cooker, these Hungarian plum dumplings, or print my editable canning labels for your jars.
Oven-Baked Plum Jam with Rum and Walnuts
A hands-off, low-sugar plum jam baked slowly in the oven, finished with dark rum and toasted walnuts. No pectin needed.
-
Large heavy pot
-
Wooden spoon
-
Sterilized jars
-
Small plate for set test
- 3 kg plums ripe, halved and pitted (about 6½ lb)
- 300 g brown sugar or white; add more for a sweeter jam
- 200 g walnut kernels roughly chopped and toasted; use less if you prefer
- 50 ml dark spiced rum or 2 vials of rum essence
- 1 tsp cinnamon optional
-
Wash the plums, halve them, and remove the pits. Spread them in a large roasting tray and scatter the brown sugar over the top. If you have time, let them sit for 30 minutes to start drawing out the juices.
-
Heat the oven to 180°C (350°F). Bake the plums uncovered, so they release their juice and slowly reduce.
-
After about 1½ to 2 hours, lower the oven to 160°C (325°F) and keep baking, until the jam is thick, dark, and glossy – about 2½ to 3 hours in total. For a smooth, magiun-style spread, blend it with a stick blender; leave it as is for a rustic jam.
-
Stir in the rum and bake for 15 more minutes so the aroma settles in. Fold in the toasted walnuts right at the end so they stay crunchy.
-
Test the set on a cold plate: drop on a little jam, wait a minute, then push it with your finger. If it wrinkles, it is ready.
-
Ladle the hot jam into clean, sterilized jars, seal, and let cool. Store sealed jars in a cool, dark place; refrigerate once opened.
How to sterilize the jars: Wash the jars well with hot water and dish soap, then rinse them very thoroughly. Place them clean (dry or damp), opening up or on a baking sheet, on the oven rack or in a tray, without letting them touch. Put the tray into a cold oven, set it to 120–150°C (250–300°F), and time 20 minutes from the moment the oven reaches temperature. Turn off the oven and let the jars cool down gradually inside before using them.
- Do not put lids with rubber seals in the oven — they can warp or the seal can melt. Sterilize those separately by boiling them in water.
- Do not wipe the inside of the jars with a cloth after sterilizing, to avoid re-contaminating them with bacteria.
Frequently Asked Questions
The oven surrounds the plums with even heat, so the whole tray reduces on its own without constant stirring or a splattering pot. It is the hands-off way to get a thick, deep jam, much easier than tending a cauldron over a fire.
No. The slow oven bake evaporates the water and concentrates the plums, and plum skins carry plenty of natural pectin. Even with little sugar, it sets into a spoonable jam given time.
Most of the rum’s alcohol cooks off during the long, slow bake, leaving mainly its warm aroma. If you would rather skip it, use two vials of rum essence instead, or leave it out.
Yes. For a smooth, magiun-style spread, blend the jam with a stick blender before jarring. Leave it as is for a rustic jam with soft pieces of fruit.
Stir the rum in near the end of baking so its aroma stays bright, and fold the toasted walnuts in during the last few minutes so they keep their crunch instead of going soft.
Sealed, sterilized jars keep in a cool, dark place for up to 6 months. Because this jam is low in sugar, once opened store it in the fridge and use it within 3 to 4 weeks.