If you're using Essential in your modpack, you've probably already noticed that FancyMenu can't customize Essential's UI. This is not FancyMenu's fault and Essential needs to fix that on their side, but there's an okay-ish workaround for now. Essential now lets you completely disable their UI stuff they add to the game.
Since Essential v1.1.1 (Oct 2022) you can switch the entire Essential overlay off with one toggle:
Title Screen ▶ Essential Settings ▶ Appearance ▶ “Essential menu layout” ⇒ OFF.
That instantly reverts the Title (and Pause) screen to Vanilla, while leaving the library portion of the mod loaded so other mods that depend on it still work. On older builds you’ll need either (a) to update, or (b) to remove Essential.