If you're trying to copy save files; it may all be for naught if the Steam Cloud auto-backup undoes your work; I recommend disabling the steam cloud before moving save files. You can always turn it back on afterwards.

To do this, right click on the game in your library and select "Properties...". Then, in the general tab, deactive the option under the "Steam Cloud" section.

And of course: back-up any of your own save files before you copy over them.

The PC Gaming Wiki is a great source for save file locations, and this game is no exception.

https://www.pcgamingwiki.com/wiki/Overcooked!

In Windows, the save file location is:

%USERPROFILE%\AppData\LocalLow\Ghost Town Games\Overcooked\


The four useful files are:

• CoopSlot_SaveFile_0.save
  
• Meta_SaveFile.save
  
• DLC1_CoopSlot_SaveFile_0.save
  
• DLC2_CoopSlot_SaveFile_0.save
  
  For achievements, you don't need the two DLC save files.
  
  I don't know if you really need Meta_SaveFile.save or not, but better safe than sorry.

My save files from playing the game can be found in this link.[drive.google.com]

Copy these until the save folder above (%USERPROFILE%\AppData\LocalLow\Ghost Town Games\Overcooked\)

On the account I tested on, the "All the Trimmings" and "Hero of Thyme" achievements unlocked immediately.

For the other achievements, you need to play a level. Steam user melmagicmage has a great guide for this already, but basically you need to:

• Finish levels 1-3, 2-1, 3-1, 4-1, 5-1 and 5-2 (you don't need 3 stars)
  
• Play the prologue and complete one recipe to get "Lettuce Begin"
  
• Play a split pad game (any level, like the prologue, by pressing T on the level selection map and changing the controls to split keyboard (or Y on a controller to the do the same) to get "Closest Friends"
  
• Play a versus game (you'll need a spare controller for this, or use JoytoKey or another virtual option to fake it) to get "Does not play well with others"
  
• Purposely start a fire in any level and put it out to get "Overcooked"

Hopefully this helps someone get that nagging "All the Trimmings" achievement if you really can't beat a level. The save files should unlock it immediately and give you access to any level, I tested them on another Steam account in my family (and someday my kids will notice and wonder how they 100%ed this game in 20 minutes).

Let me know if you need further explanation or have any thoughts in the comments.