Q. Kneidlach on the last day of Pesach is a very important minhag in our family. When can you cook kneidlach this year when the last day of Pesach is Shabbos (for those who only eat or make gebrochts (matza dipped in water or matza flour baked) only on the last day of Pesach?

A. Poskim permit preparing the kneidlach on Erev Shabbos, the Seventh Day of Pesach, even for those who strictly refrain from having matza touch water or liquids during Pesach. Although, it cannot be eaten on that same day for them, many others are lenient and eat matza shruya all Pesach, and it would be fit for them. This applies only if an Eiruv Tavshilin was done. (Machazik Brocho 467: 6, Haelef Lecha Shlomo 343, Mikroei Kodesh 2: 60, Nitei Gavriel 3: 19 et. al.)
Horav Shlomo Miller’s Shlit’a opinion is similar

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a