Here is the full list of all 32 Hell Pie achievements.
Collect everything
Get all outfits
Defeat the Hell Pie
Use private insurance
Collect all Candymeat
Collect all Unilambs
Collect all Lucky Cats
Hit 10 humans in the factory
Witness a dark ritual
Unlock Nugget Fart
Complete the Wing Horns Challenge Level
Destroy the crosses in Heaven
Bring all sexy plants together
Complete the Arm Horns challenge level
Plug in all Wi-Fi sticks
Monty Python did it with style, don't know how it's done here
Complete dining room side quest
Defeat Gluttony
Complete the Light Horns challenge level
Collect 10000 crystals
Complete the Ram Horns challenge level
Collect 5000 crystals
All Munchers freed
Defeat the boss of the Sewers
Trigger whale explosion
Complete the Sprint Horns challenge level
Buy your first outfit
Collect 1000 crystals
Collect your first ingredient
Smash Nugget against the wall
Meet Cupid
Meet Chef