According to various opinions, Ashkenazim may eat food that comprises kitniyot on Pesach (e.g., mixtures), if it is batel b'rov (see Peninei Halacha here). For example: foods comprising kitniyot additives are almost always batel b'rov, since additives are normally only added in small amounts. From what I understand from Rav Melamed, the flavour of the kitniyot-containing food is irrelevant, as is 1/60th, which is important in other areas of kashrut. The only factor is whether the kitniyot forms a majority or not. So included in this permission to eat kitniyot-containing food would be (for example) a cake comprising 49% corn flour (kitniyot) and 51% non-kitniyot ingredients, which Ashkenazim would be allowed to eat on Pesach.
Primarily, this is allowed when the kitniyot-containing food is prepared before Pesach. There is a discussion about whether Ashkenazim observing the prohibition of kitniyot would be allowed to eat these products on Pesach if they were prepared on Pesach.
Question: What are the various opinions regarding kitniyot products where the kitniyot is batel b'rov, if it was prepared on Pesach itself? Do any opinions permit a person who observes the kitniyot prohibition to eat, or even prepare, a kitniyot containing food dish on Pesach where the kitniyot is batel b'rov? Do those opinions consider this bediavad or lechatchila?