I suspect this recipe in Philippine Welser’s collection, unlike the previous one, is meant for dried plums:
47 If you want to make a plum (gwestenn) tart
Take plums and wash them cleanly in much water. Put them in a pot that is glazed on the inside and pour in good wine. Let them boil for a long time so the stones are removed easily. Then take them out and remove the stones. Prepare a tart base (bedalin) with sugar and cinnamon, and then put the plums on it one next to the other until it is full. Then sprinkle it well with sugar, cinnamon, and a little ginger and make a cut top crust. Let it bake, and when it is half baked, pour in one or two spoonfuls of this broth (the cooking liquid?) and brush it with an egg, then let it bake fully.
If this is made with dried plums, it may come out not too dissimilar to the date tart in recipe #42:
42 If you want to make a date tart
Take the dates and remove the kernels, and boil therm in good wine. When they are boiled well, place them on the tart base. Put on cinnamon, sugar, and ginger and let it bake nicely.
I wonder how well they would have held together as they were boiled, but it seems they were expected to stay discrete even after quite some softening. That suggests a rather tough, leathery consistency. Beyond that, I am sure the result was attractive. A similar combination of spices using mashed fruit is one of my favourites.
Philippine Welser (1527-1580), a member of the prominent and extremely wealthy Welser banking family of Augsburg, was a famous beauty of her day. Scandalously, she secretly married Archduke Ferdinand II of Habsburg in 1557 and followed him first to Bohemia, then to Tyrol. A number of manuscripts are associated with her, most famously a collection of medicinal recipes and one of mainly culinary ones. The recipe collection, addressed as her Kochbuch in German, was most likely produced around 1550 when she was a young woman in Augsburg. It may have been made at the request of her mother and was written by an experienced scribe. Some later additions, though, are in Philippine Welser’s own hand, suggesting she used it.
The manuscript is currently held in the library of Ambras Castle near Innsbruck as PA 1473 and was edited by Gerold Hayer as Das Kochbuch der Philippine Welser (Innsbruck 1983).