CHKN

This has to be done in Legacy mode (Creative works).

Go into the Properties of the game in Steam. Select Betas and then change Beta Participation to Legacy.

Once in Legacy, just kill 10 creatures with the slingshot.

I was able to do this in Legacy instance in Creative. (unsure if it can work in regular instance Creative/Adventure).

Spawn or tame 3 creatures.

Build 3 nests
Assign a monster to each nest. Wait

Have each monster lay 1 egg in each nest.
Once the eggs are layed then just wait some more till they hatch.
Noticed the achievement after i closed the game