This page of the Biomutant guide contains a walkthrough of the Lump Muffin side quest. We have described everything you need to do in order to complete the quest and earn the rewards.
Starting the quest
How to start: Talk to a man in town - Flibberdit.
Reward: 100 XP.
To start the quest, you need to talk to the man sitting in front of the house. He will mention a man who bakes the best pastries.