Need a tool recommendation

[Warpspeed]

Yup.
They do not say what the hysteresis is, but my link to essentially the same thing suggests it might be 15C.
If we are heating just a pad, and the rest is exposed, the pad may need to run a bit warmer anyway.
A bit of experimentation might be in order, they are not super expensive.

 

[SeaGal]

Spreadable butter?

 

[Sean Steele]

Spreadable butter?

Doesn't taste the same a plain ol' stick butter because they add oil to it. Plus, straight out of the fridge, it isn't all that spreadable and it must be refrigerated.