The recipe for a white custard tart in Philippine Welser’s collection has a companion that refers back to it. Here they are side by side:
240 How to make good tarts in several ways
To make white tarts
Firstly, you must take a Seutel (liquid measure and drinking vessel), as the Seutln are customary in this country) of the whites of eggs, one Seutel of sugar, half a Libertzen (pound) of good almonds that are most carefully and finely pounded, and also a Seutel of good milk. Pass the prepared ingredients through a sieve all together with the milk. Then make a dough of flour, sugar, and rosewater. Grease the pan with fat beforehand to prevent it burning. Make the dough as thin as paper, lay it over the pan, and place the tart or rather the abovementioned ingredients on it. Put an edge (Reuffelin) on it above all sprinkle rosewater on the tart. Beaten egg white is spread on it with a small feather, and finally sugar is sprinkled on, never stint the latter. Cover the pan and the tart diligently with a covering (überleg) and set coals above it as is needed. That way, the rosewater, egg white, and sugar will harden and draw together like a crust and the tart will be as good as marzipan.
241 To make another white tart
At the beginning, take a Putschen (pitcher) of good milk, the best that can be had, add rice according to the size and occasion of the tart, and cook the two together. But see the rice does not cook too dry. Then take a seutel of egg whites, one of sugar, and one pound of good almonds, and no more milk that is needed to pass the abovementioned ingredients through a sieve. If you make this kind of tart with a dough and edge made with rosewater, egg whites, and sugar prepared and finished exactly as is described above and above all do not stint the sugar, it will be a good tart.
Despite being quite similar in many respects, these tarts would produce a very different texture and eating experience. The fact they are both given the same name suggests that the “white” tart was a broad class. It is possible that the egg white custard of the first recipe is the ‘original’ while the rice filling of the second represents a way of making economies, though at a high level. I think it is more likely that they are variations on a theme. Like a modern hamburger or pancake, a ‘white tart’ could be many things.
Both recipes are detailed, but not easy to reconstruct with full confidence. Among the things I do not know is the quantity of a Seutel or a Putschen. The seidel is usually a drinking vessel, so we are not looking at very large containers, the Putschen a vessel for serving drinks to pour out at the table, thus likely to be larger. It seems likely to me that neither refers to a formal measure. We also do not know which pound measure the recipe refers to, though that is less problematic given the variety was not extreme.
As to the crust, we know almost nothing about it. The dough involves rosewater and a thin base of just flour and rosewater, like phyllo dough, is possible. It certainly cannot have been a short crust given it is meant to be rolled out thin ‘as paper’ (which even using sixteenth-century linen paper as a basis of comparison would be quite thin). The top layer is interesting in its own light; It sounds like an ancestral form of meringue. The sugar, egg whites, and rosewater are all supposed to be spread separately and fused during baking. Similar sixteenth-century recipes give instructions to mix sugar and egg whites before baking, though, and they are likely of one family.
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).