[candiddevmike]

Do you try to pull the butter onto your knife periodically, or do you wait somehow until it pushes the butter onto your knife? When does it become less work to just go get the butter yourself?

[DonHopkins]

You just need a self-buttering knife, like a self-licking ice cream cone:

https://en.wikipedia.org/wiki/Self-licking_ice_cream_cone