The chili pepper can be a difficult ingredient to find in Roblox Wacky Wizards since it is hidden in an underground grave. Once you know where to look, though, all it takes is completing a short obby to get the ingredient.
To find the underground obby, run toward the desert. This dry biome is located in one corner of the game world and is not too large an area. You'll know you've found it by the sand, the multiple cacti, and a small railroad within the area.
The obby is hidden below the sand, and the location won't be immediately apparent. Within the desert, there is a lone cactus placed in between two rock cliffs. The cave is behind this cactus. Check out the picture above for the exact location. If you've approached the rail road, then you've gone too far and have missed the cactus.
Running behind the cactus will drop you into a hidden cave. As you travel below, you will find an area that is a small obby. The chili pepper ingredient is on the other side of the obby. It might take a handful of tries to complete the obby, but be careful with your jumps and you should reach the chili pepper in no time.
Once you've reached the other side of the obby, tab or click on the chili pepper ingredient to equip it to your Avatar. Then, you can press Teleport to Cauldron to warp out of the obby with your chili pepper in hand.