Overcooked! 2

You have to get 3 stars in the 6 levels of the world 6. You don't need to do the Kevin's levels. Here is a playlist containing videos of all levels unlocked in 4 stars duo mode. They will show you the technique to use, but you just have to make 3 stars for this achievement.
https://www.youtube.com/playlist?list=PLTg8yNY-9NDMNpQs1RLGR...

See also below the 6 levels separately. Good game.
Level 6-1 : Level 6-2 : Level 6-3 : Level 6-4 : Level 6-5 : Level 6-6 :

This won’t be a level by level guide, but just some tips to hopefully help you get through a little easier. This game isn’t that difficult, nor was the first one, as it’s just as much about time management as it is cooking. I completed both games (story at least on 2) solo... I hear a lot of people that think that you need two or more people and that isn’t correct, though it may be more fun (and maybe harder... more people means higher scores for 3 stars. Focus on one, maybe two dishes at a time, never have a chef standing around, you can always multi task. Never forget to have clean dishes... you can’t serve food without plates. The ingredients will always show how to cook said dish (pan, boil, oven etc) look ahead at future dishes if you have moving platforms, this isn’t a real kitchen and you can toss items on the floor to prepare later. If you follow these guidelines, you should be able to complete all levels at 3 stars, solo. Any questions, just ask or message me. Hardest level imho is 6-1.