You would get mille fleur d'Uccles that are split for lavender (carrying one copy of the lav gene). Breeding those back to porcelains will result in 50% porcelain, 50% mille fleur split for lavender.
Large fowl Cochins should be a good start. Even the hatchery ones we have are annoyingly broody and can cover a good number of eggs. They won't follow a predictable schedule though.