We have looked at faux eggs for Lent before. The Dorotheenkloster MS has a series of recipes for these things.

49 Of all kinds of eggs in Lent
Take two pounds (libra) of almonds and pound them small. Grind them with sugar and add a little water so it stays white. You must not let it boil, and it must be moderately thick. You can make eggs out of that this way: Take one part of the almonds mass and colour it red with saffron so it appears like a yolk. Make as many yolks of the red part as you please, the size of egg yolks. Then take a small white cloth and make a hole in it. Lay the yolk into it put the white over it so it is shaped like an egg. Make enough for a dish this way. And ½ (pound of?) raisins, wash them and grind them small. Take a slice of a semeln loaf and crumble it into them with sweet wine to make a pheffer sauce with sugar. This is called eggs in pheffer sauce.
50 Another dish of eggs
Take a few eggs (as described in the previous recipe?) into a reidlen (small cooking vessel) and make halved eggs and lay them in there, as many as you want. And take a quarter pound (vierdung) of sugar and lay it into a pan. When it has melted, you pour it over the eggs. They lie in it as in fat. And take whites of the eggs and milk and make it as thick as soft eggs, and add sugar in place of salt.
51 A different dish of eggs
Prepare whole eggs and stick them on a spit. Make them black or yellow, and do not forget the sugar.
The first recipe is fairly straightforward. These are what we would call marzipan eggs. I am not entirely sure what the role of the cloth is, but other than that it is basically a saffron-coloured yolk surrounded by white almond-sugar paste, a reasonable simulacrum of a hard-boiled egg. They are served in a sweet sauce of raisins thickened with bread which is actually a fairly common recipe for meat sauces, sometimes referred to as a pfeffer. There is a similar, but much more ambitious recipe for faux hard-boiled eggs in their shells in the 16th-century Künstlichs und fürtrefflichs Kochbuch, so the idea did not die out.
The second and third recipes, I assume, deal with the same faux eggs rather than real ones. In the first half of #50, a strong sugar syrup is used to simulate melted fat and produce the effect of deep-fried Eier im Schmalz. Again, we have a broadly similar idea in the Inntalkochbuch, but in this case what is simulated is more like pan-fried eggs sunny side up. The second half, I assume, aims to simulate a soft egg dish usding only the white almond paste. In recipe #51, we find sparse instructions for presenting the almond paste eggs like hard-boiled eggs on a spit, another popular conceit on wealthy tables.
The Dorotheenkloster MS is a collection of 268 recipes that is currently held at the Austrian national library as Cod. 2897. It is bound together with other practical texts including a dietetic treatise by Albertus Magnus. The codex was rebound improperly in the 19th century which means the original order of pages is not certain, but the scripts used suggest that part of it dates to the late 14th century, the remainder to the early 15th century.
The Augustine Canons established the monastery of St Dorothea, the Dorotheenkloster, in Vienna in 1414 and we know the codex was held there until its dissolution in 1786, when it passed to the imperial library. Since part of the book appears to be older than 1414, it was probably purchased or brought there by a brother from elsewhere, not created in the monastery.
The text was edited and translated into modern German by Doris Aichholzer in „wildu machen ayn guet essen…“Drei mittelhochdeutsche Kochbücher: Erstedition Übersetzung, Kommentar, Peter Lang Verlag, Berne et al. 1999 on pp. 245-379.