If I put piping hot cholent onto a Kli Sheini, is it then permitted to put it on challah, even if you hold Yesh Bishul Achar Tzeliyay

Shalom uvracha, Yes, one can be lenient about this and put the very hot cholent on his bread. Detailed explanation: The reason it's permitted is that we are not talking about kli sheini, but kli shlishi. This is because the spoon or the ladle that you used to put the cholent on your plate is considered kli sheini. That makes the plate kli shlishi. The Mishna brura is lenient about this in our case (see Mishna brura 318;45,47), shmirat shabat kehilchata (chapter 1, comment 210). True, some say that since the cholent is solid and not liquid it doesn't have kli sheini (see Mishna brura 318;45). However, many poskim are lenient about this. Additionally, you don't mean to cook the bread, which makes it "psik reisha delo ichpat lei" (see shmirat shabat kehilchata chapter 1; comment 201). Additionally, if the cholent is dry it wouldn't be considered bishul achrei afiya . Only if there is liquid it would cook the bread. The Igrot Moshe permitted putting ketchup on a hot potato since some poskim permit bishul achrei bishul even with liquid and the plate considered kli shlishi. All the best!