Elden Ring - Spent too much time on a joke today

You can fight them head-on.

OR.

In peak Souls-like quests fashion, you can search for a random NPC who's in another town, and buy him a shrubbery so they may let you pass.

And later on, you can fight a tougher but optional variant of this boss, named Knight Who Says Ekki-Ekki-Ekki-Ekki-PTANG Zoom-Boing Z'nourrwringmm.