Question: May one eat matza balls (kneidlach) or meat balls made from matza-meal on Erev Pesach?
Answer: Rambam (Chametz Umatza 6:12) writes that one must not eat matza on Erev Pesach. The Mishna Berura (471:12) notes that some have the minhag not to eat matza from Rosh Chodesh Nissan. R’ Moshe Feinstein (Igros Moshe OC 1:155) notes that some abstain from eating matza for 30 days before Pesach as according to one view in the Gemara (Pesachim 6a) this is when our Pesach preparations begin.
The Rema (OC 471:2) writes that one cannot eat matza that had been broken up and kneaded with wine and oil. Thus, one would not be able to eat matza brei, etc. on Erev Pesach. The Mishna Berura (444:8; 471:20) explains that even if one does so, it is still considered to be matza. However, if one cooked the matza, to make kneidlach one would be able to eat it up until sha’ah asiris, three halachic hours before Yom Tov.
R’ Shmuel Wosner (Shevet HaLevi 8:117) writes that this prohibition includes cakes baked from matza meal (See Piskei Teshuvos 471:3).
According to R’ Shlomo Zalman Auerbach (Halichos Shlomo, Pesach 8:4), one may eat food made with matza meal providing that it doesn’t have the ‘form of bread’. R’ Ovadia Yosef (Yabia Omer OC 6:39) writes that the prohibition only applies to actual matza but cake made with matza meal can be eaten.
In conclusion, one may eat kneidlach and meat balls made with matza meal. There are different customs as to whether one can eat biscuits and cakes made with matza meal on Erev Pesach.