From the Super Mario Wiki
Château Chanterelle is a location from Paper Mario: Color Splash. The path leading here is unlocked after getting the yellow Mini Paint Star in Sunglow Ridge, and unlocks paths leading to Mondo Woods and Marmalade Valley. The Toad Professor lives here with his pet Chain Chomp, Princess. The spike for the door in Kiwano Temple is found here. The Piggy Bank Thing card can be found here in the barn.
After entering the area, a Toad shows Mario the professor's house, which has an orange Mini Paint Star on top. When Mario enters the house, another Toad explains that the professor has went for a walk in Mondo Woods with his pet Chain Chomp, Princess. Exiting the house's back door, Mario can go north and enter a Warp Pipe that takes him to the orange Mini Paint Star.
To get the green Mini Paint Star, Mario must enter Princess's doghouse, which brings him underground. He can enter a Warp Pipe and go behind a barn. Opening the left barn door reveals the Piggy Bank Thing. Mario must align the lines on the doors so that they form a path he can Cutout to reach the Mini Paint Star.
Names in other languages